molecules

Review Recent Uses of N,,N-Dimethylformamide and N,N-Dimethylacetamide as Reagents

JeanJean LeLe BrasBras andand JacquesJacques MuzartMuzart **

InstitutInstitut dede ChimieChimie MolMoléculaireéculaire dede Reims,Reims, CNRS—UniversitCNRS—Universitéé dede ReimsReims Champagne-Ardenne,Champagne-Ardenne, B.P.B.P. 1039, 1039, 51687 Reims CEDEX 2,2, France;France; [email protected]@univ-reims.fr ** Correspondence: Correspondence: [email protected];[email protected]; Tel.:Tel.:+33-3-26913237 +33-3-26913237 Academic Editor: Michal Szostak Academic Editor: Michal Szostak


Received: 13 July 2018; Accepted: 31 JulyJuly 2018; Published: 3 August 2018


Abstract:Abstract: NN,,N-Dimethylformamide and N,,N-dimethylacetamide are multipurpose reagents whichwhich deliver their own H, C, N and O atoms for the synthesissynthesis of a variety of compounds under a number of differentdifferent experimentalexperimental conditions.conditions. The review mainly highlights the correspondingcorresponding literatureliterature published overover thethe lastlast years.years.

Keywords: N,N-dimethylformamide; DMF; N,N-dimethylacetamide;-dimethylacetamide; DMAc; amination; amination; amidation; amidation; thioamidation; formylation;formylation; carbonylation;carbonylation; cyanation;cyanation; insertion;insertion; cyclizationcyclization

1. Introduction The organic, organic, organometallic organometallic and and bioorganic bioorganic transformations transformations are areextensively extensively carried carried out in out N,N in- Ndimethylformamide,N-dimethylformamide (DMF) (DMF) or N or,N-dimethylacetamideN,N-dimethylacetamide (DMAc). (DMAc). These These two twopolar polar solvents solvents are not are notonly only use usefor fortheir their dissolution dissolution properties, properties, but but also also as as multipurpose multipurpose reagents. reagents. They They participate participate in a number of processes andand serve as a source of variousvarious building blocks giving one or more of their own atoms (Scheme1 1).).

O C HnC NMe2 H H C O n=0,1,2 O O C CH2 R N C Me O CN C O H NMe NMe 2 C Me n C R N n=1,2 R NMe n Me CH n=1,2 n O n=0,1,2 C C NMe2 R C O O NMe2 C C R R

Scheme 1.1. Fragments from DMDM (R(R == H or Me) used in synthesis.

In 2009, one of us reviewed the different roles of DMF, highlighting that DMF is much more than In 2009, one of us reviewed the different roles of DMF, highlighting that DMF is much more a solvent [1]. Subsequently, this topic has been documented by the teams of Jiao [2] and Sing [3]. For than a solvent [1]. Subsequently, this topic has been documented by the teams of Jiao [2] and Sing [3]. of a book devoted to solvents as reagents in organic synthesis, we wrote a chapter summarizing the

Molecules 2018, 23, x; doi: FOR PEER REVIEW www.mdpi.com/journal/molecules Molecules 2018, 23, 1939; doi:10.3390/molecules23081939 www.mdpi.com/journal/molecules Molecules 2018, 23, 1939 2 of 31 Molecules 2018, 23, x FOR PEER REVIEW 2 of 29

Forreactions of a book consuming devoted DMF to solvents and DMAc as reagents as carbon, in organic hydrogen, synthesis, nitrogen we an wroted/or oxygen a chapter sources summarizing [4]. This thebook reactions chapter consumingtentatively DMFcovered and the DMAc literature as carbon, up to hydrogen,middle 2015. nitrogen The pres and/orent mini-review oxygen sources focuses [4]. Thison recent book chapterreactions tentatively which involve covered DM the (DM literature = DMF up or to DMAc) middle as 2015. a reagent The present although mini-review some key focuses older onpapers recent are reactions also included which for involve context. DM Processes (DM = DMF which orDMAc) necessitate as a the reagent prerequisite although synthesis some key of older DM papersderivatives are alsosuch included as the Vilsmeier-Haack for context. Processes reagents which [5] and necessitate DMF dimethyl the prerequisite acetal [6] are synthesis not surveyed, of DM derivativesbut a few suchreactions as the of Vilsmeier-Haack the present review reagents invo [5]lve and the DMF in-situ dimethyl formation acetal [of6] area Vilsmeier-type not surveyed, butintermediate a few reactions (Vilsmeier-type of the present reagents review involvehave been the in-situextensively formation used. of aSearch Vilsmeier-type on 26 June intermediate 2018 for (Vilsmeier-type“Vilsmeier” with reagents SciFinder have led been to 4379 extensively entries). used.Color Searchequations, on 26based June on 2018 literature for “Vilsmeier” proposals, with are SciFinderused to easily led to 4379visualize entries). the ColorDM equations,atom origin. based Wh onen literatureuncertainty proposals, is expressed are used by to easilythe authors visualize or thesuspected DM atom by us, origin. the atom When is typed uncertainty in italic. is expressedMechanistic by schemes the authors are not or suspectedreported, but by Scheme us, the atom2 [7– is35] typed summarizes in italic. different Mechanistic proposed schemes reactions are not of reported, DM with but the Scheme corresponding2[ 7–35] summarizes literature references, different proposedwhere DM reactions acts as either of DM a withnucleophilic the corresponding or electroph literatureilic reagent, references, or leads whereto neutral, DM ionic acts as or either radical a nucleophilicspecies. The or review electrophilic is divided reagent, in orSections leads to depending neutral, ionic on or the radical DM species. fragment(s) The review which is dividedis (are) inincorporated Sections depending into the reaction on the DM product. fragment(s) which is (are) incorporated into the reaction product.

SchemeScheme 2.2. ReactionsReactions ofof DMDM ((RR= =H H or or Me Me).).

2.2.C C Fragment Fragment AerobicAerobic carbonylationcarbonylation underunder nickel/coppernickel/copper oror palladium/silverpalladium/silver synergistic catalysis occurredoccurred efficientlyefficiently using the the Me Me group group of of DMF DMF as as the the C Csour source,ce, affording affording cyclic cyclic carbonylated carbonylated compounds, compounds, via viathe thedirecting directing group-assist group-assisteded activation activation of ofa aC(sp C(sp2)–H2)–H or or C(sp C(sp3)-H3)-H bond bond (Equations (Equations (1) (1) and and (2) (2) [36], [36], EquationsEquations (3) and (4) [[37]).37]). Shifting from DMF to DMAc greatly decreased the yields (Equations (1) andand (3)).(3)).

Molecules 2018, 23, x FOR PEER REVIEW 2 of 29 reactions consuming DMF and DMAc as carbon, hydrogen, nitrogen and/or oxygen sources [4]. This book chapter tentatively covered the literature up to middle 2015. The present mini-review focuses on recent reactions which involve DM (DM = DMF or DMAc) as a reagent although some key older papers are also included for context. Processes which necessitate the prerequisite synthesis of DM derivatives such as the Vilsmeier-Haack reagents [5] and DMF dimethyl acetal [6] are not surveyed, but a few reactions of the present review involve the in-situ formation of a Vilsmeier-type intermediate (Vilsmeier-type reagents have been extensively used. Search on 26 June 2018 for “Vilsmeier” with SciFinder led to 4379 entries). Color equations, based on literature proposals, are used to easily visualize the DM atom origin. When uncertainty is expressed by the authors or suspected by us, the atom is typed in italic. Mechanistic schemes are not reported, but Scheme 2 [7– 35] summarizes different proposed reactions of DM with the corresponding literature references, where DM acts as either a nucleophilic or electrophilic reagent, or leads to neutral, ionic or radical species. The review is divided in Sections depending on the DM fragment(s) which is (are) incorporated into the reaction product.

Scheme 2. Reactions of DM (R = H or Me).

2. C Fragment Aerobic carbonylation under nickel/copper or palladium/silver synergistic catalysis occurred efficiently using the Me group of DMF as the C source, affording cyclic carbonylated compounds, via the directing group-assisted activation of a C(sp2)–H or C(sp3)-H bond (Equations (1) and (2) [36],

EquationsMolecules 2018 (3), 23 and, 1939 (4) [37]). Shifting from DMF to DMAc greatly decreased the yields (Equations3 of (1) 31 and (3)).

Molecules 2018, 23, x FOR PEER REVIEW 3 of 29 Molecules 2018, 23, x FOR PEER REVIEW 3 of 29

The Me group of DMF was also involved in the cyanation of the C(sp2)-H bond of arenes The MeMe group group of of DMF DMF was was also also involved involved in the in cyanation the cyanation of the C(spof the2)-H C(sp bond2)-H of arenesbond of catalyzed arenes catalyzed with an heterogeneous copper catalyst (Equation (5)) [38]. withcatalyzed an heterogeneous with an heterogeneous copper catalyst copper (Equation catalyst (5))(Equation [38]. (5)) [38].

3. CH Fragment 3.CH CH Fragment Fragment Treatment of indole at 130 °C with suprastoichiometric amounts of CuI, t-BuOOH and AcOH in Treatment of indole at 130 °C◦ with suprastoichiometric amounts of CuI, t-BuOOH and AcOH in DMAcTreatment under air of indoleafforded at 130the correspondingC with suprastoichiometric C3-formylation amounts product of (Equation CuI, t-BuOOH (6)) [39]. and Such AcOH a DMAc under air afforded the corresponding C3-formylation product (Equation (6)) [39]. Such a inreaction DMAc also under occurred air afforded with N the-methylindole corresponding using C3-formylation CuI and CF3CO product2H in (EquationDMAc under (6)) oxygen [39]. Such [40]. a reaction also occurred with N-methylindole using CuI and CF3CO2H in DMAc under oxygen [40]. reactionThe CH fragment also occurred came with fromN the-methylindole NMe2 moiety using [39,40]. CuI In and DMF, CF 3bothCO2 Hprocedures in DMAc led under to C3-cyanation oxygen [40]. The CH fragment came from the NMe2 moiety [39,40]. In DMF, both procedures led to C3-cyanation The(see CHbelow, fragment Equation came (25)). from the NMe2 moiety [39,40]. In DMF, both procedures led to C3-cyanation (see below, EquationEquation (25)).(25)).

Cycloadditions leading to symmetrical tetrasubstituted pyridines using the Me group of DMF Cycloadditions leading to symmetrical tetrasubstituted pyridines using the Me group of DMF as the CH source have been carried out using either ketoxime carboxylates with Ru catalysis as the CH source have been carried out using either ketoxime carboxylates with Ru catalysis (Equation (7)) [41], or arones with both iodine and ammonium persulfate mediation (Equation (8)) (Equation (7)) [41], or arones with both iodine and ammonium persulfate mediation (Equation (8)) [42]. [42].

Molecules 2018, 23, x FOR PEER REVIEW 3 of 29

The Me group of DMF was also involved in the cyanation of the C(sp2)-H bond of arenes catalyzed with an heterogeneous copper catalyst (Equation (5)) [38].

3. CH Fragment Treatment of indole at 130 °C with suprastoichiometric amounts of CuI, t-BuOOH and AcOH in DMAc under air afforded the corresponding C3-formylation product (Equation (6)) [39]. Such a reaction also occurred with N-methylindole using CuI and CF3CO2H in DMAc under oxygen [40].

MoleculesThe CH2018 fragment, 23, 1939 came from the NMe2 moiety [39,40]. In DMF, both procedures led to C3-cyanation4 of 31 (see below, Equation (25)).

Cycloadditions leading to symmetrical tetrasubstituted pyridines using the Me group of DMF as theCycloadditions CH source have leading been to symmetricalcarried out using tetrasubstituted either ketoxime pyridines carboxylates using the Mewith group Ru catalysis of DMF as(Equation the CH (7)) source [41], haveor arones been with carried both out iodine using and either ammonium ketoxime persulfate carboxylates mediation with (Equation Ru catalysis (8)) (EquationMolecules[42]. 2018 (7)), 23 [,41 x FOR], or PEER arones REVIEW with both iodine and ammonium persulfate mediation (Equation (8))4 [of42 29]. Molecules 2018, 23, x FOR PEER REVIEW 4 of 29

2,4-Diarylpyridines were also synthetized from Ru-catalyzed reaction of acetophenones with ammonium2,4-Diarylpyridines acetate and DMF were as also source synthetized of the N fromand CH Ru-catalyzed atoms, respectively reaction (Equation of acetophenonesacetophenones (9)) [43]. with ammonium acetate and DMF as source ofof thethe NN andand CHCH atoms,atoms, respectivelyrespectively (Equation(Equation (9))(9)) [[43].43].

With sodium azide as the nitrogen source, DMAc was superior to DMF to deliver the CH fragmentWith ofsodium the copper-catalyzed azide as the nitrogen domino source, reaction DMs Acof wasaryl superiorhalides whichto DMF led to to deliver imidazo the [1,2-CH cfragment]quinazolines,With sodiumof the quinazolinones copper-catalyzed azide as the nitrogen or imidazo[4,5- domino source, reaction DMAcc]quinolones wass of superioraryl (Equations halides to DMF (10)–(12))which to deliver led [44]. to the imidazo CH fragment [1,2- ofc]quinazolines, the copper-catalyzed quinazolinones domino or reactions imidazo[4,5- of arylc]quinolones halides which (Equations led to (10)–(12)) imidazo [1,2- [44].c ]quinazolines, quinazolinones or imidazo[4,5-c]quinolones (Equations (10)–(12)) [44].

In contrast to the above examples, the Cu-catalyzed cyclization leading to 6H-chromeno[4,3- b]quinolin-6-onesIn contrast to (Equation the above (13)) examples, with incorporation the Cu-catalyzed of a CH cyclization belonging leading to DMF to occurred6H-chromeno[4,3- with low yieldb]quinolin-6-ones when t-BuOOH (Equation was the (13)) oxidant. with incorporationShifting to t-butyl of a CHperbenzoate belonging allowe to DMFd an occurred effective with reaction low [45].yield Forwhen the t -BuOOHsynthesis was of 4-acyl-1,2,3-triazolesthe oxidant. Shifting fromto t-butyl Cu-catalyzed perbenzoate cycloaddition allowed an toeffective acetophenones reaction (Equation[45]. For the (14)), synthesis K2S2O8 wasof 4-acyl-1,2,3-triazoles superior to t-BuOOH, from (t-BuO) Cu-catalyzed2 and (PhCO cycloaddition2)2 [46]. Yields to decreasedacetophenones with (EquationDMAc instead (14)), of K DMF2S2O8 (Equationswas superior (13) to andt-BuOOH, (14)). (t-BuO)2 and (PhCO2)2 [46]. Yields decreased with DMAc instead of DMF (Equations (13) and (14)).

Molecules 2018, 23, x FOR PEER REVIEW 4 of 29

2,4-Diarylpyridines were also synthetized from Ru-catalyzed reaction of acetophenones with ammonium acetate and DMF as source of the N and CH atoms, respectively (Equation (9)) [43].

With sodium azide as the nitrogen source, DMAc was superior to DMF to deliver the CH

Moleculesfragment2018 of, 23 the, 1939 copper-catalyzed domino reactions of aryl halides which led to imidazo 5[1,2- of 31 c]quinazolines, quinazolinones or imidazo[4,5-c]quinolones (Equations (10)–(12)) [44].

In contrast to the above examples, the Cu-catalyzed cyclization leading to 6H-chromeno[4,3- b]quinolin-6-onesIn contrast to (Equation the above (13)) examples, with incorporation the Cu-catalyzed of a CH cyclization belonging leading to DMF to occurred 6H-chromeno[4,3- with low byield]quinolin-6-ones when t-BuOOH (Equation was the (13)) oxidant. with Shifting incorporation to t-butyl of perbenzoate a CH belonging allowe tod DMFan effective occurred reaction with low[45]. yieldFor the when synthesist-BuOOH of 4-acyl-1,2,3-triazoles was the oxidant. Shifting from Cu-catalyzed to t-butyl perbenzoate cycloaddition allowed to acetophenones an effective reaction(Equation [ 45(14)),]. K For2S2O the8 was synthesis superior ofto t 4-acyl-1,2,3-triazoles-BuOOH, (t-BuO)2 and from (PhCO Cu-catalyzed2)2 [46]. Yields cycloaddition decreased with to acetophenonesDMAc instead of (Equation DMF (Equations (14)), K (13)2S2O and8 was (14)). superior to t-BuOOH, (t-BuO)2 and (PhCO2)2 [46]. YieldsMolecules decreased 2018, 23, x FOR with PEER DMAc REVIEW instead of DMF (Equations (13) and (14)). 5 of 29

The insertion of a CH from the NMe2 of DM under metal-free conditions has been reported for the synthesisThe insertion of cyclic of a compounds CH from the such NMe as:2 of DM under metal-free conditions has been reported for the synthesis of cyclic compounds such as: - pyrimidines from t-BuOOH-mediated reaction between acetophenones, amidines and DMF (Equation (15)) [47],

- substituted phenols also from three components cycloadditions (Equation (16)) [48],

- 3-acylindoles from 2-alkenylanilines (Equation (17)) [49],

- benzimidazoles and benzothiazole from o-phenylenediamine or 2-aminobenzenethiol through carbon dioxide-mediated cyclization (Equation (18)) [50].

Molecules 2018, 23, x FOR PEER REVIEW 5 of 29

Molecules 2018, 23, x FOR PEER REVIEW 5 of 29

Molecules 2018, 23, x FOR PEER REVIEW 5 of 29

Molecules 2018, 23, 1939 6 of 31 The insertion of a CH from the NMe2 of DM under metal-free conditions has been reported for

the synthesis of cyclic compounds such as: The insertion of a CH from the NMe2 of DM under metal-free conditions has been reported for

- thepyrimidines synthesis of fromcyclict -BuOOH-mediatedcompounds such as: reaction between acetophenones, amidines and DMF - Thepyrimidines insertion from of a CHt-BuOOH-mediated from the NMe2 of reactionDM under between metal-free acetophenones, conditions has amidines been reported and DMF for (Equation (15)) [47], the- synthesis(Equationpyrimidines of (15)) cyclic from [47], compounds t -BuOOH-mediated such as: reaction between acetophenones, amidines and DMF - pyrimidines(Equation (15)) from [47], t-BuOOH-mediated reaction between acetophenones, amidines and DMF (Equation (15)) [47],

- substituted phenols also from three components cycloadditions (Equation (16)) [48],

- - substitutedsubstituted phenols phenols also also from from three three components components cycloadditions cycloadditions (Equation (Equation (16)) (16)) [48 [48],],

- substituted phenols also from three components cycloadditions (Equation (16)) [48],

- 3-acylindoles from 2-alkenylanilines (Equation (17)) [49],

- 3-acylindoles from 2-alkenylanilines (Equation (17)) [49],

- - 3-acylindoles3-acylindoles from from 2-alkenylanilines 2-alkenylanilines (Equation (Equation (17)) (17)) [49 [49],],

- benzimidazoles and benzothiazole from o-phenylenediamine or 2-aminobenzenethiol through

- benzimidazolescarbon dioxide-mediated and benzothiazole cyclization from (Equation o-phenylenediamine (18)) [50]. or 2-aminobenzenethiol through

- benzimidazolescarbon dioxide-mediated and benzothiazole cyclization from (Equation o-phenylenediamine (18)) [50]. or 2-aminobenzenethiol through - benzimidazolescarbon dioxide-mediated and benzothiazole cyclization from (Equationo-phenylenediamine (18)) [50]. or 2-aminobenzenethiol through carbon dioxide-mediated cyclization (Equation (18)) [50]. Molecules 2018, 23, x FOR PEER REVIEW 6 of 29

O NH2 N CO2 (50 atm) R1 C Me R1 C H + H N (18) H2O, 150 °C, 5 h Z ZH Me Z=NHorS (2 equiv) Z = NH, 5 examples: 93-97% 1 Z=S,R =H:86%

2 4.CH4. CH2 Fragment Fragment TheThe coupling coupling of indolesof indoles or or imidazo[1,2- imidazo[1,2-a]pyridinesa]pyridines to affordto afford heterodiarylmethanes heterodiarylmethanes with with DMF DMF as as thethe methylenating methylenating reagent reagent occurred occurred in fair in tofair high to high yields yields with awith CuI acatalyst CuI catalyst associated associated to t-BuOOH to t-BuOOH [51] 2 2 8 or[51] K2S 2orO 8K[52S ]O (Equations [52] (Equations (19)–(21)). (19)–(21)). Use of Us DMAce of DMAc was less was efficient. less efficient.

In DMAc, the I2/t-BuOOH association catalyzed the formation of methylene-bridged bis-1,3- dicarbonyl compounds from aryl β-ketoesters or β-ketoamides (Equation (22)). Lower yields were obtained with I2/K2S2O8 in DMAc or DMF [9]. Subjection 1,3-diphenylpropane-1,3-dione or ethyl 3- oxobutanoate to the I2/t-BuOOH/DMAc did not afford the bridged compounds.

A Mannich reaction leading to β-amino ketones with DMF as the formaldehyde source has been reported in the presence of t-BuOOH and catalytic amounts of an N-heterocyclic carbene, SnCl2 and NEt3 (Equation (23)) [11].

Molecules 2018, 23, x FOR PEER REVIEW 6 of 29 Molecules 2018, 23, x FOR PEER REVIEW 6 of 29 NH O 2 O CO (50 atm) N 1 NH2 Me 2 1 N R + C CO2 (50 atm) R C H (18) R1 + H C N Me R1 C H (18) ZH H N H2O, 150 °C, 5 h Z Me H2O, 150 °C, 5 h Z ZH Me Z=NHorS (2 equiv) Z = NH, 5 examples: 93-97% Z=NHorS (2 equiv) Z = NH, 5 examples: 93-97% Z=S,R1 =H:86% 1 Z=S,R =H:86%

4. CH2 Fragment 4. CH2 Fragment The coupling of indoles or imidazo[1,2-a]pyridines to afford heterodiarylmethanes with DMF as The coupling of indoles or imidazo[1,2-a]pyridines to afford heterodiarylmethanes with DMF as the methylenating reagent occurred in fair to high yields with a CuI catalyst associated to t-BuOOH Moleculesthe methylenating2018, 23, 1939 reagent occurred in fair to high yields with a CuI catalyst associated to t-BuOOH7 of 31 [51] or K2S2O8 [52] (Equations (19)–(21)). Use of DMAc was less efficient. [51] or K2S2O8 [52] (Equations (19)–(21)). Use of DMAc was less efficient.

In DMAc, the I2/t-BuOOH association catalyzed the formation of methylene-bridged bis-1,3- In DMAc, the I2/t-BuOOH association catalyzed the formation of methylene-bridged bis-1,3- dicarbonylIn DMAc, compounds the I2 /fromt-BuOOH aryl β-ketoesters association or catalyzed β-ketoamides the (Equation formation (22)). of methylene-bridgedLower yields were bis-1,3-dicarbonyldicarbonyl compounds compounds from aryl from β-ketoesters aryl β-ketoesters or β-ketoamides or β-ketoamides (Equation (Equation (22)). Lower (22)). Lower yields yields were obtained with I2/K2S2O8 in DMAc or DMF [9]. Subjection 1,3-diphenylpropane-1,3-dione or ethyl 3- wereobtained obtained with I with2/K2S I2O/K8 inS DMAcO in or DMAc DMF or [9]. DMF Subjection [9]. Subjection 1,3-diphenylpropane-1,3-dione 1,3-diphenylpropane-1,3-dione or ethyl or3- oxobutanoate to the I22/t-BuOOH/DMAc2 2 8 did not afford the bridged compounds. ethyloxobutanoate 3-oxobutanoate to the I2 to/t-BuOOH/DMAc the I2/t-BuOOH/DMAc did not afford did not the afford bridged the compounds. bridged compounds.

A Mannich reaction leading to β-amino ketones with DMF as the formaldehyde source has been A Mannich reaction leading to β-amino ketones with DMF as the formaldehyde source has been reportedA Mannich in the presence reaction leadingof t-BuOOH to β-amino and catalytic ketones amounts with DMF of an as theN-heterocyclic formaldehyde carbene, source SnCl has2 been and reported in the presence of t-BuOOH and catalytic amounts of an N-heterocyclic carbene, SnCl2 and reportedNEt3 (Equation in the presence(23)) [11]. of t-BuOOH and catalytic amounts of an N-heterocyclic carbene, SnCl2 and NEt3 (Equation (23)) [11]. NEtMolecules3 (Equation 2018, 23, x (23)) FOR PEER [11]. REVIEW 7 of 29

The study of an unexpected reaction due to the oxidation of DMAc with aqueous t-BuOOH The study of an unexpected reaction due to the oxidation of DMAc with aqueous t-BuOOH (Equation (24)) showed the formation of MeCONMe(CH2OH) and MeCON(CH2OH)2, these unusual (Equation (24)) showed the formation of MeCONMe(CH OH) and MeCON(CH OH) , these unusual species delivering the methylene group [12]. 2 2 2 species delivering the methylene group [12].

5. NC Fragment While CuI under oxidative and acidic conditions led, in DMAc, to the C3-formylation of indole and N-methylindole (Equation (6)), reactions in DMF led to C3-cyanations (Equation (25)) [39,40]. Cyanation of electron-rich arenes and benzaldehydes was also carried out (Equation (26)) [39]. Monitoring the course of the reaction indicated a cyanation arising via the formyl compounds [39,40]. Moreover, 3-iodo indole could also be involved in the formation of the cyano product [40].

Laser ablation of silver nitrate in DMF led to silver cyanide (Equation (27)) [53].

Molecules 2018, 23, x FOR PEER REVIEW 7 of 29 Molecules 2018, 23, x FOR PEER REVIEW 7 of 29

The study of an unexpected reaction due to the oxidation of DMAc with aqueous t-BuOOH Molecules(EquationThe2018 study(24)), 23, 1939showed of an unexpected the formation reaction of MeCONMe(CH due to the oxidation2OH) and of MeCON(CH DMAc with2OH) aqueous2, these t -BuOOHunusual8 of 31 species(Equation delivering (24)) showed the methylene the formation group of [12]. MeCONMe(CH 2OH) and MeCON(CH2OH)2, these unusual species delivering the methylene group [12].

5.N NCC Fragment Fragment 5. NC Fragment While CuI under oxidative and acidic conditions led, in DMAc, to the C3-formylation of indole and NWhile-methylindole CuI under (Equation oxidative (6)), (6)),and reactions reactionsacidic conditions in in DMF DMF led,led led into DMAc,C3-cyanations to the C3-formylation (Equation (Equation (25)) (25)) of [39,40]. [ 39indole,40]. Cyanationand N-methylindole of electron-rich (Equation arenes (6)), and reactions benzaldehydes in DMF led was to also C3-cyanations carried out out (Equation (Equation (25)) (26)) (26)) [39,40]. [39]. [39]. MonitoringCyanation of the electron-rich course of the arenesreaction and indicated benzaldehydes a cyanation was arising also via viacarried the the formyl formyl out (Equation compounds compounds (26)) [39,40]. [39 [39].,40]. Moreover,Monitoring 3-iodo3-iodo the course indoleindole of couldcould the reaction alsoalso bebe indicated involvedinvolved a inin cyanation thethe formationformation arising ofof via thethe the cyanocyano formyl productproduct compounds [[40].40]. [39,40]. Moreover, 3-iodo indole could also be involved in the formation of the cyano product [40].

Laser ablation of silver nitrate in DMF led to silver cyanide (Equation (27)) [53]. MoleculesLaser 2018 ablation, 23, x FOR of PEER silver REVIEW nitrate in DMF led to silver cyanide (Equation (27)) [53]. 8 of 29 Laser ablation of silver nitrate in DMF led to silver cyanide (Equation (27)) [53].

6.N NMeMe2 FragmentFragment This chapter is divided in sections correspondingcorresponding toto thethe typetype ofof functionfunction reactingreacting withwith DM.DM.

6.1. Aryl Halides RefluxingRefluxing chloropyridines in DM or DMAc afforded thethe correspondingcorresponding aminopyridinesaminopyridines (Equation (28)) [25]. [25]. The The amination amination of of aryl aryl chlorides chlorides and and 3-pyridinyl 3-pyridinyl chloride chloride with with DMF DMF occurred occurred at atroom room temperature temperature in inthe the presence presence of of potassium potassium t-butoxidet-butoxide and and a a carbenic carbenic palladium catalyst (Equation (29)) [[27].27].

6.2. Alkylarenes

Oxidation of methylarenes and ethylarenes at 80 °C in DMF using catalytic amounts of both I2 and NaOH [31] or n-Bu4NI [32] associated to aqueous t-BuOOH under air led to benzylic oxidation and incorporation of the NMe2 fragment to afford benzamides (Equation (30)) or α-ketoamides (Equation (31)).

6.3. Alkenes Hydrocarbonylation of terminal alkenes and norbornene followed by acyl metathesis with DM occurred under Pd catalysis, CO pressure and in the presence of ammonium chloride or N-methyl-2- pyrrolidone hydrochloride (NMP·HCl) (Equations (32) and (33)) [54]. From alkenes, the selectivity towards linear and branched products depended on the catalytic system (Equation (32)). DMF and DMAc afforded similar results.

Molecules 2018, 23, x FOR PEER REVIEW 8 of 29

6. NMe2 Fragment This chapter is divided in sections corresponding to the type of function reacting with DM.

6.1. Aryl Halides Refluxing chloropyridines in DM or DMAc afforded the corresponding aminopyridines (Equation (28)) [25]. The amination of aryl chlorides and 3-pyridinyl chloride with DMF occurred at Moleculesroom temperature2018, 23, 1939 in the presence of potassium t-butoxide and a carbenic palladium catalyst9 of 31 (Equation (29)) [27].

6.2. Alkylarenes ◦ Oxidation of methylarenes and ethylarenes at 80 °CC in DMFDMF usingusing catalyticcatalytic amountsamounts ofof bothboth II22 and NaOH [[31]31] or nn-Bu-Bu4NI [32] [32] associated to aqueous t-BuOOH under air led to benzylicbenzylic oxidationoxidation and incorporation of the NMeNMe2 fragment to afford benzamidesbenzamides (Equation (30)) oror αα-ketoamides-ketoamides (Equation (31)).(31)).

6.3. Alkenes Hydrocarbonylation of of terminal terminal alkenes alkenes and and norb norborneneornene followed followed by acyl by acyl metathesis metathesis withwith DM DMoccurred occurred under under Pd catalysis, Pd catalysis, CO pressure CO pressure and in the and presence in the of presence ammonium of ammonium chloride or N chloride-methyl-2- or Npyrrolidone-methyl-2-pyrrolidone hydrochloride hydrochloride (NMP·HCl) (Equations (NMP·HCl) (32) (Equations and (33)) (32)[54]. and From (33)) alkenes, [54]. Fromthe selectivity alkenes, thetowards selectivity linear towards and branched linear and products branched depended products on depended the catalytic on the system catalytic (Equation system (32)). (Equation DMF(32)). and DMFDMAc and afforded DMAc similar afforded results. similar results.

Molecules 2018, 23, 1939 10 of 31 MoleculesMolecules 20182018,, 2323,, xx FORFOR PEERPEER REVIEWREVIEW 99 ofof 2929

6.4.6.4. Acids Acids Copper,Copper, palladiumpalladium palladium andand and rutheniumruthenium ruthenium catalystscatalysts catalysts associatedassociated associated toto oxidantsoxidants to oxidants andand DMFDMF and were DMFwere usedused were forfor used thethe amidationforamidation the amidation ofof cinnamiccinnamic of cinnamic acidsacids [29][29] acids andand [29 carboxyliccarboxylic] and carboxylic acidsacids [55][55] acids (Equations(Equations [55] (Equations (34)(34) andand (34) (35)).(35)). and N (35)).N,,NN-- DimethylbenzamideNDimethylbenzamide,N-Dimethylbenzamide waswas oneone was ofof one thethe ofproductsproducts the products obtainedobtained obtained fromfrom thethe from CuCuIIII the-catalyzed-catalyzed CuII-catalyzed oxidationoxidation oxidation ofof flavonolflavonol of [56].flavonol[56]. [56].

Metal-freeMetal-free conditionsconditions andand DMFDMF werewere usedused for:for: Metal-free conditions and DMF were used for: -- thethe amidationamidation ofof acidsacids promotedpromoted withwith propylphosphonicpropylphosphonic anhydrideanhydride associatedassociated toto HClHCl atat 130130 °C°C - (Equation(Equationthe amidation (36))(36)) of [15],[15], acids promoted with propylphosphonic anhydride associated to HCl at 130 ◦C -- thethe(Equation aminationamination (36)) ofof [ 15 acidsacids], employingemploying aa hypervalenthypervalent iodineiodine reagentreagent atat roomroom temperaturetemperature (Equation(Equation - (37))(37))the [35]. amination[35]. MesityliodineMesityliodine of acids diacetatediacetate employing waswas superiorsuperior a hypervalent toto thethe otherother iodine hypervalenthypervalent reagent atiodineiodine room reagents,reagents, temperature whilewhile oxidantsoxidants(Equation suchsuch (37)) asas [35 II22].,, tt-BuOOH, Mesityliodine-BuOOH, NaIONaIO diacetate44 oror KK22SS2 was2OO88 diddid superior notnot mediatemediate to the other thethe amidationamidation hypervalent reactionreaction iodine [35]. reagents,[35]. while oxidants such as I2, t-BuOOH, NaIO4 or K2S2O8 did not mediate the amidation reaction [35].

Molecules 2018, 23, 1939 11 of 31 MoleculesMoleculesMolecules 20182018 2018,,, ,2323 23,,, ,xxx x FORFORFOR FOR PEERPEERPEER PEER REVIEWREVIEWREVIEW REVIEW 101010 ofof of 2929 29

TreatmentTreatmentTreatment ofofof arylaceticarylaceticarylacetic andandand cinnamiccinnamiccinnamic acids acidsacids withwithwith base,base,base, sulfursulfursulfur and andand DMFDMFDMF atatat 100–120 100–120100–120 °C°C°C ledledled tototo Treatment of arylacetic and cinnamic acids with base, sulfur and DMF at 100–120 ◦C led to decarboxylativedecarboxylativedecarboxylative thioamidationthioamidation thioamidation (Equations(Equations (Equations (38)(38) (38) andand and (39)(39) (39))) ) [7].[7]. [7]. InhibitionInhibition Inhibition ofof of thethe the processprocess process inin in thethe the presencepresence presence decarboxylative thioamidation (Equations (38) and (39)) [7]. Inhibition of the process in the presence ofofof TEMPOTEMPO TEMPO oror or BHTBHT BHT indicatedindicated indicated aa a radicalradical radical involvementinvolvementinvolvement involvement ininin in thethethe the transformations.transformations.transformations. transformations. of TEMPO or BHT indicated a radical involvement in the transformations.

6.5. Carbonylated Compounds 6.5.6.5. Carbonylated Carbonylated Compounds Compounds Reaction of 2-arylquinazolin-4(3H)-ones with TsCl and t-BuOK in DM provided the ReactionReaction ofofof 2-arylquinazolin-4(3 2-arylquinazolin-4(32-arylquinazolin-4(3H)-onesHH)-ones)-ones with withwith TsCl andTsClTsClt-BuOK andand intt-BuOK-BuOK DM provided inin DMDM the provided correspondingprovided thethe corresponding 4-(dimethylamino)quinazolines in good yields, especially in DMF (Equation (40)). corresponding4-(dimethylamino)quinazolinescorresponding 4-(dimethylamino)quinazolines4-(dimethylamino)quinazolines in good yields, inin especially goodgood yields,yields, in DMF especiallyespecially (Equation inin DMF (40)).DMF (Equation These(Equation reactions (40)).(40)). These reactions occurred via the formation of the 2-aryl-4-(tosyloxy)quinazolines [57]. TheseoccurredThese reactionsreactions via the occurredoccurred formation viavia of thethe the formationformation 2-aryl-4-(tosyloxy)quinazolines ofof thethethe 2-aryl-4-(tosyloxy)quinazolines2-aryl-4-(tosyloxy)quinazolines2-aryl-4-(tosyloxy)quinazolines [57]. [57].[57].[57].

VariousVarious amidesamides havehave beenbeen synthetisynthetizedzed fromfrom aldehydesaldehydes andand DMFDMF usingusing t-BuOOHt-BuOOH andand aa VariousVarious amidesamides have have been been synthetized synthetized from from aldehydes aldehydes and DMF and using DMFt -BuOOHusing t-BuOOH and a recyclable and a recyclablerecyclable heterogeneousheterogeneous catalystcatalyst—a—a carbon–nitrogencarbon–nitrogen embeddedembedded cocobaltbalt nanoparticlenanoparticle denoteddenoted asas heterogeneousrecyclable heterogeneous catalyst—a catalyst carbon–nitrogen—a carbon–nitrogen embedded cobaltembedded nanoparticle cobalt nanoparticle denoted as Co@C-N600denoted as Co@C-N600Co@C-N600 (Equation(Equation (41))(41)) [33].[33]. TheThe samesame transformationtransformation ofof benzaldehydesbenzaldehydes waswas subsequentlysubsequently (EquationCo@C-N600 (41)) (Equation [33]. The (41)) same [33]. transformation The same transformation of benzaldehydes of benzaldehydes was subsequently was reported subsequently using reportedreported using using Co/Al Co/Al hydrotalcite-derived hydrotalcite-derived catalysts catalysts [58]. [58]. Co/Alreported hydrotalcite-derived using Co/Al hydrotalcite-derived catalysts [58]. catalysts [58].

CopperCopperCopper oxideoxide oxide andand and iodineiodine iodine mediatedmediated mediated thethe the reactionreaction reaction ofof of acetophenonesacetophenones acetophenones withwith with sulfursulfur sulfur andand and DMFDMF DMF toto to affordafford afford ααα-arylketothioamides-arylketothioamides-arylketothioamides (Equation(Equation (Equation (42))(42)) (42)) viavia via thethe the formationformation formation ofof of αα α-iodoacetophenones-iodoacetophenones-iodoacetophenones [59].[59]. [59].

Molecules 2018, 23, 1939 12 of 31

Copper oxide and iodine mediated the reaction of acetophenones with sulfur and DMF to afford αMolecules-arylketothioamides 20182018,, 2323,, xx FORFOR PEERPEER (Equation REVIEWREVIEW(42)) via the formation of α-iodoacetophenones [59]. 1111 ofof 2929

Elemental sulfur and the NMe2 moiety of DMF or DMAc was also used for the DBU-promoted ElementalElemental sulfursulfur andand thethe NMeNMe22 moietymoiety of of DMF DMF or or DMAc DMAc was was also usedused forfor thethe DBU-promotedDBU-promoted synthesis of thioamides from aldehydes2 (Equation (43)) or arones (Equation (44)) [60], the latter synthesissynthesis of of thioamidesthioamides from from aldehydesaldehydes (Equation (Equation (43)) (43)) or or aronesarones (Equation(Equation (44)) (44)) [[60],[60],60], thethe latterlatter undergoing an efficient Willgerodt-Kindler reaction [61,62]. undergoingundergoing anan efficientefficient Willgerodt-KindlerWillgerodt-Kindler reactionreaction [[61,62].61,62].

6.6. Benzyl Amines 6.6.6.6. Benzyl Amines The recyclable Co/Al catalysts used above in DMF for the amidation of benzaldehydes also led TheThe recyclablerecyclable Co/AlCo/Al catalystscatalysts usedused aboveabove in in DMF DMF for for the the amidation amidation of of benzaldehydes benzaldehydes also also led led to to benzamides from benzylamines and t-BuOOH (Equation (45)). These transformations would benzamidestoto benzamidesbenzamides from fromfrom benzylamines benzylaminesbenzylamines and tandand-BuOOH tt-BuOOH-BuOOH (Equation (Equation(Equation (45)). These(45)).(45)). transformationsTheseThese transformationstransformations would involve wouldwould involve benzaldehydes as intermediates [58]. benzaldehydesinvolveinvolve benzaldehydesbenzaldehydes as intermediates asas intermediatesintermediates [58]. [58].[58].

6.7.6.7. Nitriles NaOHNaOH mediated, at room temperature, the the effi efficientcientcient reactionreaction ofof thethe CNCN groupgroup ofof 4-oxo-2,4- 4-oxo-2,4- diphenylbutanenitrilediphenylbutanenitrile with with DMF DMF to to afford afford the the corresponding corresponding γ-ketoamide-ketoamideγ-ketoamide (Equation(Equation (Equation (46))(46)) [63]. (46))[63]. SuchSuch [63]. Suchcompoundscompounds compounds werewere alsoalso were obtainedobtained also obtained fromfrom thethe from dominodomino the rere dominoaction of reaction chalcones of with chalcones malononitrile with malononitrile and NaOH andinin DMFDMF NaOH [63].[63]. in DMF [63].

6.8.6.8. Sulfur Compounds SulfonamidesSulfonamides werewere synthetized:synthetized:

--- fromfromfrom thiophenols,thiophenols, DMFDMF andand airair viavia anan an oxygen-activatedoxygen-activated oxygen-activated radical radical process process mediated mediated by by copper copper salts salts andand cinnamic cinnamic acid acid (Equation (Equation (47)) (47)) [64], [64],

Molecules 2018, 23, 1939 13 of 31 Molecules 2018, 23, x FOR PEER REVIEW 12 of 29

MoleculesMolecules 2018 2018, 23,, x23 FOR, x FOR PEER PEER REVIEW REVIEW 12 of12 29 of 29 CuCl (1 equiv) Molecules 2018, 23, x FOR PEER REVIEW 12 of 29 Molecules 2018, 23, x FOR PEER REVIEW Cu(OAc) (1 equiv) Me 12 of 29 CuClCuCl (1 equiv)(12 equiv) O cinnamic acid (1 equiv) N Cu(OAc)CuClCu(OAc) (1 (1 equiv)2 equiv)(1 equiv) MeMe ArSH CuCl (12 equiv) O OS Me(47) cinnamicCu(OAc)cinnamic acid (1 acid (1 equiv) equiv) (1 equiv) Ar MeN N HCONMe2,2 air, 110 °C, 24 h O MeSO Me ArSHArSH Cu(OAc)2 (1 equiv) S Me(47)(47) cinnamicHCONMe acid, air,12 (1 110 examples,equiv) °C, 24 h46-90%Ar ArO N ArSH HCONcinnamicMe2, air,acid2 110 (1 equiv) °C, 24 h SONOMe(47) ArSH HCONMe , air, 11012 examples, °C, 24 h 46-90%Ar S Me(47) or reaction of sodium sulfonates2 with12 examples, N-iodosuccinimide 46-90%Ar O and DMF pretreated with t-BuOK HCONMe2, air, 110 °C, 24 h O or reaction of sodium sulfonates with12N examples,-iodosuccinimide 46-90% and DMF pretreated with t-BuOK or (Equationorreaction reaction of (48)) ofsodium sodiumvia, probably, sulfonates sulfonates sulfonyl with with12 N iodidesexamples,-iodosuccinimide N-iodosuccinimide (Equation 46-90% (49))and and [65].DMF DMF pretreated pretreated with with t-BuOK t-BuOK (Equation (48)) via, probably, sulfonyl iodides (Equation (49)) [65]. or(Equation (Equationreaction (48)) of (48)) sodium via, via, probably, probably,sulfonates sulfonyl sulfonyl with iodides N iodides-iodosuccinimide (Equation (Equation (49)) and(49)) [65]. DMF[65]. pretreated with t-BuOK or reaction of sodium sulfonates with N-iodosuccinimide and DMF pretreated with t-BuOK (Equation (48)) via, probably, sulfonyl iodides (Equation (49)) [65]. (Equation (48)) via, probably, sulfonyl iodides (Equation (49)) [65].

7. O Fragment

7.O O7. Fragment FragmentO DMFFragment delivered its oxygen atom to 1,2-cyclic sulfamidates via nucleophilic displacement at the 7. Oquaternary Fragment center to afford, after hydrolysis, an aminoalcohol (Equation (50)) [17]. 7. O DMFFragmentDMF delivered delivered its oxygenits oxygen atom atom toto 1,2-cyclic1,2-cyclicto 1,2-cyclic sulfamidatessulfamidates sulfamidates via via nucleophilicnucleophilic nucleophilic displacement displacement at theat the quaternaryquaternaryDMF delivered center center toto afford,itsafford,to oxygenafford, afterafter after atom hydrolysis,hydrolysis, hydrolysis, to 1,2-cyclic anan aminoalcoholanaminoalcohol sulfamidates aminoalcohol (Equation(Equation via (Equation nucleophilic (50))(50)) (50)) [[17].17 ].displacement[17]. at the DMF delivered its oxygen atom to 1,2-cyclic sulfamidates via nucleophilic displacement at the quaternary center to afford, after hydrolysis, an aminoalcohol (Equation (50)) [17]. quaternary center to afford, after hydrolysis, an aminoalcohol (Equation (50)) [17].

DMF was also the oxygen source leading to an imidazolinone from the reaction with the Cu-

carbene complex and the borate salt depicted in Equation (51) [66]. DMFDMF was was also also the the oxygen oxygen source source leading leading to anto animidazolinone imidazolinone from from the the reaction reaction with with the the Cu- Cu- carbenecarbeneDMF complex was wascomplex also also and theand the the oxygen the oxygenborate borate sourcesalt source salt depicted leadingdepicted leading in to Equationin toan Equation animidazolinone imidazolinone (51) (51) [66]. [66]. from from the thereaction reaction with with the Cu- the DMF was also the oxygen source leading to an imidazolinone from the reaction with the Cu- carbeneCu-carbene complex complex and andthe theborate borate salt saltdepicted depicted in Equation in Equation (51) (51) [66]. [66 ]. carbene complex and the borate salt depicted in Equation (51) [66].

The I2/CuO association allowed the α-hydroxylation of arones in abstracting, via the α- iodoarone,The I 2the/CuO oxygen association atom of allowedDMF (Equation the α-hydroxylation (52)) [18]. of arones in abstracting, via the α- The I2/CuO association allowed the α-hydroxylation of arones in abstracting, via the α- iodoarone,iodoarone,The I2 /CuOthe the oxygen oxygenassociation atom atom of allowed DMFof DMF (Equation the(Equation α-hydroxylation (52)) (52)) [18]. [18]. of arones in abstracting, via the α- The I I/CuO2/CuO associationassociation allowed allowed the theα-hydroxylation α-hydroxylation of arones of arones in abstracting, in abstracting, via the α -iodoarone,via the α- iodoarone,2 the oxygen atom of DMF (Equation (52)) [18]. theiodoarone, oxygen the atom oxygen of DMF atom (Equation of DMF (52)) (Equation [18]. (52)) [18].

8. C=O Fragment

8. C=O8. C=O WithFragment Fragment DMF as the CO surrogate, quinazolinones have been prepared at 140–150 °C 8. C=O FragmentWith DMF as the CO surrogate, quinazolinones have been prepared at 140–150 °C 8. C=O- With viaFragment DMF C(sp 2as)-H the bond CO activationsurrogate, andquinazolinon annulationes using have beenPd/C prepared[67] or Pd(OAc) at 140–1502 [8], °C in the presence of WithK2 SDMF2O8, CF as2 3 theCO 2COH and surrogate, O2 (Equation quinazolinon (53)), es have been prepared at 140–150 °C - - viaWithvia C(sp DMF C(sp2)-H as)-H bond the bond CO activation activationsurrogate, and andquinazolinon annulation annulation usinges usinghave Pd/C beenPd/C [67] prepared [67] or Pd(OAc)or Pd(OAc) at 140–1502 [8],2 [8], in °C thein the presence presence of of 2 - viaK2SK C(sp2O2S82,O CF8)-H, CF3CO bond3CO2H 2and Hactivation and O2 O(Equation2 (Equation and annulation (53)), (53)), using Pd/C [67] or Pd(OAc)2 [8], in the presence of - via C(sp2)-H bond activation and annulation using Pd/C [67] or Pd(OAc)2 [8], in the presence of K2S2O8, CF3CO2H and O2 (Equation (53)), K2S2O8, CF3CO2H and O2 (Equation (53)),

Molecules 2018, 23, 1939 14 of 31

8. C=O Fragment With DMF as the CO surrogate, quinazolinones have been prepared at 140–150 ◦C

2 - via C(sp )-H bond activation and annulation using Pd/C [67] or Pd(OAc)2 [8], in the presence of MoleculesK2S 20182O8, ,23 CF, x 3FORCO 2PEERH and REVIEW O2 (Equation (53)), 13 of 29 MoleculesMoleculesMolecules 2018 20182018, 23,, 2323x FOR,, xx FORFOR PEER PEERPEER REVIEW REVIEWREVIEW 13 of1313 29 ofof 2929

or carbon dioxide-mediated cyclization of 2-aminobenzonitrile (Equation (54)) [50]. This latter or ororreactioncarbon carboncarbonor carbon dioxide-mediatedwould dioxide-mediateddioxide-mediated dioxide-mediated involve a Vilsmeier-Haack cyclization cyclizationcyclization cyclization of ofof 2-aminobenzonitriletype of2-aminobenzonitrile2-aminobenzonitrile 2-aminobenzonitrileintermediate and (Equation did (Equation(Equation (Equation not occur (54)) (54))(54)) (54))with [50]. [50].[50]. [DMAc.50 This]. ThisThis latter latterlatterlatter reactionreactionreactionreaction would wouldwould involve would involveinvolve involve a Vilsmeier-Haack aa Vilsmeier-HaackVilsmeier-Haack a Vilsmeier-Haack type typetype intermediate type intermediateintermediate intermediate and andand did did anddid not notnot did occur occuroccur not with occur withwith DMAc. with DMAc.DMAc. DMAc.

A carbonylative Suzuki-type reaction leading to diarylketones arose in DMF under Ni catalysis at A100 carbonylativeAA °C carbonylativecarbonylative (Equation Suzuki-type (55)), Suzuki-typeSuzuki-type IPr = bis(2,6-diisopropylphenyl)imidazol-2-ylidene) reaction reactionreaction leading leadingleading to todiarylketonesto diarylketonesdiarylketones arose arosearose in inDMFin DMFDMF [13], under underorunder Pd Ni catalysis Ni Nicatalysis catalysiscatalysis and A carbonylative Suzuki-type reaction leading to diarylketones arose in DMF under Ni catalysis at at 100atatUV 100100 °C light °C °C(Equation (Equation(Equationassistance (55)), (55)), (55)),at roomIPr IPrIPr = bis(2,6-diisopropylphenyl)imidazol-2-ylidene) =temperature= bis(2,6-diisopropylphenyl)imidazol-2-ylidene)bis(2,6-diisopropylphenyl)imidazol-2-ylidene) (Equation (56)) [68]. [13], [13],[13], or orPdor PdPd catalysis catalysiscatalysis and andand 100 ◦C (Equation (55)), IPr = bis(2,6-diisopropylphenyl)imidazol-2-ylidene) [13], or Pd catalysis and UVUVUV light lightlight assistance assistanceassistance at atroomat roomroom temperature temperaturetemperature (Equation (Equation(Equation (56)) (56))(56)) [68]. [68].[68]. UV light assistance at room temperature (Equation (56)) [68].

Catalytic amounts of a ruthenium pincer complex and t-BuOK led, at 165 °C, to symmetric and Catalytic amounts of a ruthenium pincer complex and t-BuOK led, at 165 °C, to symmetric and unsymmetricCatalyticCatalyticCatalytic amounts amountsNamounts,N’-disubstituted of ofofa ruthenium aa rutheniumruthenium ureas pincer pincerpincerfrom complex primary complexcomplex and am andand inest-BuOK tt-BuOK-BuOK and led,DMF led,led, at (Equation atat165 165165 °C, ◦°C, C,to (57)) totosymmetric symmetricsymmetric [69]. and andand unsymmetric N,N’-disubstituted ureas from primary amines and DMF (Equation (57)) [69]. unsymmetricunsymmetricunsymmetric N, NN,’-disubstituted,NN’-disubstituted’-disubstituted ureas ureasureas from fromfrom primary primaryprimary am aminesaminesines and andand DMF DMFDMF (Equation (Equation(Equation (57)) (57))(57)) [69]. [[69].69 ].

At 120 °C under CuBr2 catalysis, o-iodoanilines reacted with potassium sulfide and DMF, At 120 °C under CuBr2 catalysis, o-iodoanilines reacted with potassium sulfide and DMF, leadingAtAt 120 120to °Cbenzothiazolones °C under under CuBr CuBr2 catalysis, 2(Equation catalysis, o -iodoanilines(58)) o-iodoanilines [70]. reacted reacted with with potassium potassium sulfide sulfide and and DMF, DMF, leadingleadingleading to tobenzothiazolonesto benzothiazolonesbenzothiazolones (Equation (Equation(Equation (58)) (58))(58)) [70]. [70].[70].

Molecules 2018, 23, x FOR PEER REVIEW 13 of 29

or carbon dioxide-mediated cyclization of 2-aminobenzonitrile (Equation (54)) [50]. This latter reaction would involve a Vilsmeier-Haack type intermediate and did not occur with DMAc.

A carbonylative Suzuki-type reaction leading to diarylketones arose in DMF under Ni catalysis at 100 °C (Equation (55)), IPr = bis(2,6-diisopropylphenyl)imidazol-2-ylidene) [13], or Pd catalysis and UV light assistance at room temperature (Equation (56)) [68].

Catalytic amounts of a ruthenium pincer complex and t-BuOK led, at 165 °C, to symmetric and unsymmetric N,N’-disubstituted ureas from primary amines and DMF (Equation (57)) [69].

Molecules 2018, 23, 1939 15 of 31

At 120 °C◦ under CuBr2 catalysis, o-iodoanilines reacted with potassium sulfide and DMF, At 120 C under CuBr2 catalysis, o-iodoanilines reacted with potassium sulfide and DMF, leading leadingto benzothiazolones to benzothiazolones (Equation (Equation (58)) [ 70(58))]. [70].

Molecules 2018, 23, x FOR PEER REVIEW 14 of 29

Molecules 2018, 23, x FOR PEER REVIEW 14 of 29 9. C=ONMe2 Fragment 9. C=ONMe 2 Fragment 9. C=ONPotassiumMe2 Fragment persulfate-promoted the reacti reactionon of pyridines with DMF to provide N,,N-- dimethylpicolinamidesPotassium persulfate-promoted (Equation (Equation (59)) (59)) the[71], [71 ], reactiwhile whileon the theof oxidative oxidativepyridines carbamoylation carbamoylationwith DMF ofto ofisoquinolineprovide isoquinoline N ,NN-- II II Noxides,dimethylpicolinamides-oxides, with with also also DMF, DMF, (Equation was was catalyzed catalyzed (59)) [71],by by Pdwhile Pd inin thethe the oxidative presence presence carbamoylationof of ytterbium ytterbium oxide oxideof isoquinoline as as base andand N- tetrabutylammoniumoxides, with also DMF, acetate,acetate, was thethecatalyzed latterlatter mediatingmediating by PdII in thethe the N-ON-O presence reductionreduction of (Equation (Equationytterbium (60))(60)) oxide [[72].72 ].as base and tetrabutylammonium acetate, the latter mediating the N-O reduction (Equation (60)) [72].

Alkynylation of DMF leading to N,N-dimethylamides was produced with peroxides and either Alkynylation of DMF leading to N,N-dimethylamides was produced with peroxides and either an hypervalent alkynyl iodide under Ag catalysis (Equation (61)) [73], or a terminal alkyne under Cu an hypervalentAlkynylation alkynyl of DMF iodide leading under to Ag N,N catalysis-dimethylamides (Equation was (61)) produced [73], or a terminalwith peroxides alkyne and under either Cu catalysis (Equation (62)) [34]. catalysisan hypervalent (Equation alkynyl (62)) iodide [34]. under Ag catalysis (Equation (61)) [73], or a terminal alkyne under Cu catalysis (Equation (62)) [34].

A peroxide was also used for the carbamoylation of 4-arylcoumarin with DMF (Equation (63)) [74]. AA peroxideperoxide was was also also used used for for the the carbamoylation carbamoylation of 4-arylcoumarinof 4-arylcoumarin with with DMF DMF (Equation (Equation (63)) (63)) [74]. [74].

α-Ketoamides were obtained from the domino reaction of toluenes with DMF using (t-BuO) 2, Cs2CO3 and catalytic amounts of n-Bu4NI (Equation (64)) [75]. α-Ketoamides were obtained from the domino reaction of toluenes with DMF using (t-BuO)2, Cs2CO3 and catalytic amounts of n-Bu4NI (Equation (64)) [75].

Molecules 2018, 23, x FOR PEER REVIEW 14 of 29

9. C=ONMe2 Fragment Potassium persulfate-promoted the reaction of pyridines with DMF to provide N,N- dimethylpicolinamides (Equation (59)) [71], while the oxidative carbamoylation of isoquinoline N- oxides, with also DMF, was catalyzed by PdII in the presence of ytterbium oxide as base and tetrabutylammonium acetate, the latter mediating the N-O reduction (Equation (60)) [72].

Alkynylation of DMF leading to N,N-dimethylamides was produced with peroxides and either an hypervalent alkynyl iodide under Ag catalysis (Equation (61)) [73], or a terminal alkyne under Cu catalysis (Equation (62)) [34].

MoleculesA peroxide2018, 23, 1939 was also used for the carbamoylation of 4-arylcoumarin with DMF (Equation16 (63)) of 31 [74].

α-Ketoamides were obtained from the domino reaction of toluenes with DMF using (t-BuO)2, α-Ketoamides were obtained from the domino reaction of toluenes with DMF using (t-BuO)2, Cs2CO3 and catalytic amounts of n-Bu4NI (Equation (64)) [75]. CsMolecules2CO3 2018and, 23 catalytic, x FOR PEER amounts REVIEW of n -Bu4NI (Equation (64)) [75]. 15 of 29 Molecules 2018,, 23,, xx FORFOR PEERPEER REVIEWREVIEW 15 of 29

At 100 °C in DMF, Cu catalyst associated to t-BuOOH led to unsymmetrical ureas from 2- At 100100◦ C°C in in DMF, DMF, Cu Cu catalyst catalyst associated associated to t-BuOOH to t-BuOOH led to unsymmetricalled to unsymmetrical ureas from ureas 2-oxindoles from 2- oxindolesAt 100 (Equation °C in DMF, (65)) Cu [76]. catalyst The peroxide associated would to t-BuOOH mediate ledthe tocleavage unsymmetrical reaction, ureas and wasfrom the 2- (Equationoxindoles (65))(Equation [76]. The (65)) peroxide [76]. The would peroxide mediate would the cleavage mediate reaction, the cleavage and was reaction, the oxygen and sourcewas the of oxygenoxindoles source (Equation of the (65)) benzylic [76]. carbonyl.The peroxide That wouldresulted mediate in a ketoamine the cleavage which reaction, undergone and wasthe Cu-the theoxygen benzylic source carbonyl. of the Thatbenzylic resulted carbonyl. in a ketoamine That resulted which in undergone a ketoamine the Cu-catalyzedwhich undergone reaction the withCu- catalyzedoxygen source reaction of withthe benzylic DMF/t-BuOOH, carbonyl. leading That resulted to the urea. in a ketoamine which undergone the Cu- DMF/catalyzedt-BuOOH, reaction leading with DMF/ to thet-BuOOH, urea. leading to the urea.

10. H Fragment 10.H H Fragment Fragment Semihydrogenation of diaryl alkynes occurred under Ru (Equation (66)) [77] and Pd [78] Semihydrogenation of diaryl alkynes occurred under Ru (Equation (66)) [77] and Pd [78] catalysisSemihydrogenation with DMF and water ofof diaryl diaryl as hydrogen alkynes alkynes occurred source. occurred under under Ru (Equation Ru (Equation (66)) [ 77(66))] and [77] Pd [and78] catalysisPd [78] withcatalysis DMF with and DMF water and as hydrogenwater as hydrogen source. source.

Cobalt porphyrins catalyzed the hydrogenation transfer from DMF to the C(sp3)-C(sp3) bond of Cobalt porphyrins catalyzed the hydrogenation transfer from DMF to the C(sp3)-C(sp3) bond of [2.2]paracyclophaneCobalt porphyrins (Equation catalyzed (67)) the [79]. hydrogenation DMF was al transferso involved from in DMF the Ni-catalyzed to the C(sp3)-C(sp intramolecular3) bond of [2.2]paracyclophane (Equation (67)) [79]. DMF was also involved in the Ni-catalyzed intramolecular [2.2]paracyclophanehydroarylations depicted (Equation in Equation (67)) [79 (68)]. DMF [14]. was also involved in the Ni-catalyzed intramolecular hydroarylations depicted inin EquationEquation (68)(68) [14].[14]. hydroarylations depicted in Equation (68) [14].

11. RC Fragment 11. RC Fragment New metal-catalyzed and metal-free conditions involving the CH of the formyl group of DMF New metal-catalyzed and metal-free conditions involving the CH of the formyl group of DMF have Newbeen metal-catalyzedreported for cyclizations and metal-free leading conditions to heterocycles involving (Equations the CH (69) of the[80–82] formyl and group (70) [83]). of DMF have been reported for cyclizations leading to heterocycles (Equations (69) [80–82] and (70) [83]).

Molecules 2018, 23, x FOR PEER REVIEW 15 of 29

At 100 °C in DMF, Cu catalyst associated to t-BuOOH led to unsymmetrical ureas from 2- oxindoles (Equation (65)) [76]. The peroxide would mediate the cleavage reaction, and was the oxygen source of the benzylic carbonyl. That resulted in a ketoamine which undergone the Cu- catalyzed reaction with DMF/t-BuOOH, leading to the urea.

10. H Fragment Semihydrogenation of diaryl alkynes occurred under Ru (Equation (66)) [77] and Pd [78] catalysis with DMF and water as hydrogen source.

Cobalt porphyrins catalyzed the hydrogenation transfer from DMF to the C(sp3)-C(sp3) bond of Molecules[2.2]paracyclophane2018, 23, 1939 (Equation (67)) [79]. DMF was also involved in the Ni-catalyzed intramolecular17 of 31 hydroarylations depicted in Equation (68) [14].

11.11.R RCC Fragment Fragment NewNew metal-catalyzedmetal-catalyzed and metal-free conditions involving the CH of the formylformyl groupgroup ofof DMFDMF haveMoleculeshave beenbeen 2018 reportedreported, 23, x FOR for forPEER cyclizationscyclizations REVIEW leadingleading toto heterocyclesheterocycles (Equations(Equations (69)(69) [[80–82]80–82] andand (70)(70) [[83]).83]).16 of 29 Molecules 2018, 23, x FOR PEER REVIEW 16 of 29

2-Methylbenzimidazoles were obtained from PhSiH3-assisted delivery of the CMe of DMAc to 2-Methylbenzimidazoles2-Methylbenzimidazoles were obtained from PhSiHPhSiH3-assisted delivery of the CMe of DMAcDMAc toto benzene-1,2-diamines (Equation (71)) [82]. 3 benzene-1,2-diamines (Equation(Equation (71))(71)) [[82].82].

Addition of p-tolyllithium to DMF followed by reaction with hydroxylamine hydrochloride Addition of p-tolyllithium to DMF followed by reaction with hydroxylamine hydrochloride affordedAddition 4-methylbenzaldehyde of p-tolyllithium tooxime DMF (Equation followed by(72)). reaction The latter with underwent hydroxylamine cycloaddition hydrochloride with afforded 4-methylbenzaldehyde oxime (Equation (72)). The® latter underwent cycloaddition with affordeddiphenylphosphoryl 4-methylbenzaldehyde azide or, in oximethe presence (Equation of Oxone (72)). The®, with latter diethylacetylene underwent cycloaddition dicarboxylate with to diphenylphosphoryl azide or, in the presence of Oxone , with diethylacetylene dicarboxylate to diphenylphosphorylprovide the corresponding azide 5-aryltetrazole or, in the presence or 3-arylisoxazole, of Oxone®, with respectively diethylacetylene [84]. dicarboxylate to provide the corresponding 5-aryltetrazole or 3-arylisoxazole, respectively [84]. provide the corresponding 5-aryltetrazole or 3-arylisoxazole, respectively [84].

12. RCNMe2 Fragment 12. RCNMe2 Fragment Dihydropyrrolizino[3,2-b]indol-10-ones were isolated in fair to high yields from a Cs2CO3- Dihydropyrrolizino[3,2-b]indol-10-ones were isolated in fair to high yields from a Cs2CO3- promoted domino reaction leading to the formation of three bonds with incorporation of the HCNMe promoted domino reaction leading to the formation of three bonds with incorporation of the HCNMe of DMF. Such a reaction-type with incorporation of the MeCNMe also occurred in DMAc but with a of DMF. Such a reaction-type with incorporation of the MeCNMe also occurred in DMAc but with a low yield (Equation (73)) [26]. low yield (Equation (73)) [26].

Molecules 2018, 23, x FOR PEER REVIEW 16 of 29 Molecules 2018, 23, x FOR PEER REVIEW 16 of 29

2-Methylbenzimidazoles were obtained from PhSiH3-assisted delivery of the CMe of DMAc to 2-Methylbenzimidazoles were obtained from PhSiH3-assisted delivery of the CMe of DMAc to benzene-1,2-diamines (Equation (71)) [82].

Addition of p-tolyllithium to DMF followed by reaction with hydroxylamine hydrochloride afforded 4-methylbenzaldehyde oxime (Equation (72)). The latter underwent cycloaddition with afforded 4-methylbenzaldehyde oxime (Equation (72)). The® latter underwent cycloaddition with diphenylphosphorylMolecules 2018, 23, 1939 azide or, in the presence of Oxone®,, withwith diethylacetylenediethylacetylene dicarboxylatedicarboxylate18 of toto 31 provide the corresponding 5-aryltetrazole or 3-arylisoxazole, respectively [84].

12. RCNMe2 Fragment 12.R RCNCNMeMe2 FragmentFragment

Dihydropyrrolizino[3,2-b]indol-10-ones were isolated in fair to high yields from a Cs2CO3- Dihydropyrrolizino[3,2-bb]indol-10-ones]indol-10-ones were were isolated isolated in in fair fair to high yields from aa CsCs22CO3-- promoted domino reaction leadingleading toto the formation of three bonds with incorporation of the HCNMe of DMF. SuchSuch aa reaction-typereaction-type withwith incorporation of the MeCNMe also also occurred occurred in in DMAc DMAc but but with with a a lowlow yield yield (Equation (Equation (73))(73)) [[26].[26].26].

Molecules 2018, 23, x FOR PEER REVIEW 17 of 29 Molecules 2018, 23, x FOR PEER REVIEW 17 of 29

13.R RC-OC-O Fragment Fragment 13. RC-O Fragment

A 1:1 mixture of CuOCuO andand II22 ledled thethe αα-formyloxylation-formyloxylation or α-acetoxylation of methylketones by A 1:1 mixture of CuO and I2 led the α-formyloxylation or α-acetoxylation of methylketones by DMF or DMAc, respectively (Equation (74)). α-Iodoketones would be the intermediates as indicated DMF or DMAc, respectively (Equation (74)). α-Iodoketones would be the intermediates as indicated by the reaction of 2-iodo-1-(4-methoxyphenyl)ethanone (Equation (75)). Traces of water delivered the by the reaction of 2-iodo-1-(4-me 2-iodo-1-(4-methoxyphenyl)ethanonethoxyphenyl)ethanone (Equation(Equation (75)). Traces of water delivered the carbonyl oxygen [16]. carbonyl oxygen [[16].16].

Stereoinversion of the secondary alcohols of a number of carbocyclic substrates was carried out Stereoinversion of of the the secondary secondary alcohols alcohols of of a nu a numbermber of ofcarbocyclic carbocyclic subs substratestrates was was carried carried out via their triflylation followed by treatment with aqueous DMF (Equation (76)) and subsequent outvia viatheir their triflylation triflylation followed followed by bytreatment treatment with with aqueous aqueous DMF DMF (Equation (Equation (76)) (76)) and subsequentsubsequent methanolysis [85]. A one pot stereoinversion process was reported. methanolysis [[85].85]. A one pot stereoinversion process was reported.

The formyl group of DMF was involved in the triflic anhydride-mediated domino reaction The formyl group of DMF was involved in the triflic anhydride-mediated domino reaction depicted in Equation (77) [86]. depicted in Equation (77) [86].

Chloroformyloxylation and chloroacetoxylation of olefinic substrates were performed with Chloroformyloxylation and chloroacetoxylation of olefinic substrates were performed with PhICl2 and either wet DMF or DMAc (Equation (78)) [87]. Styrenes suffered also difunctionalization PhICl2 and either wet DMF or DMAc (Equation (78)) [87]. Styrenes suffered also difunctionalization using aryl diazonium salts and Ru photocatalysis in wet DM (Equation (79)) [28]. using aryl diazonium salts and Ru photocatalysis in wet DM (Equation (79)) [28].

Molecules 2018, 23, x FOR PEER REVIEW 17 of 29

13. RC-O Fragment

A 1:1 mixture of CuO and I2 led the α-formyloxylation or α-acetoxylation of methylketones by DMF or DMAc, respectively (Equation (74)). α-Iodoketones would be the intermediates as indicated by the reaction of 2-iodo-1-(4-methoxyphenyl)ethanone (Equation (75)). Traces of water delivered the carbonyl oxygen [16].

Stereoinversion of the secondary alcohols of a number of carbocyclic substrates was carried out via their triflylation followed by treatment with aqueous DMF (Equation (76)) and subsequent methanolysis [85]. A one pot stereoinversion process was reported.

Molecules 2018, 23, 1939 19 of 31

The formyl group of DMFDMF waswas involvedinvolved inin thethe triflictriflic anhydride-mediatedanhydride-mediated domino reaction depicted in Equation (77) [[86].86].

Chloroformyloxylation and chloroacetoxylation of olefinic substrates were performed with Chloroformyloxylation and chloroacetoxylation of olefinic substrates were performed with PhICl2 PhICl2 and either wet DMF or DMAc (Equation (78)) [87]. Styrenes suffered also difunctionalization andPhICl either2 and weteither DMF wet or DMF DMAc or DMAc (Equation (Equation (78)) [87 (78))]. Styrenes [87]. Styrenes suffered suffered also difunctionalization also difunctionalization using using aryl diazonium salts and Ru photocatalysis in wet DM (Equation (79)) [28]. arylusing diazonium aryl diazonium salts and salts Ru and photocatalysis Ru photocatalysis in wet in DM wet (Equation DM (Equation (79)) [28 (79))]. [28].

Molecules 2018, 23, x FOR PEER REVIEW 18 of 29

14.R RC=OC=O FragmentFragment

Metal-catalyzed or CO2-mediated C–N and N–H bond metathesis reactions between primary or Metal-catalyzed or CO2-mediated C–N and N–H bond metathesis reactions between primary or secondary amines and DM provided the transamidation products, that is formamides or acetamides (Equation(Equation (80))(80)) [[88–91].88–91].

Formylation of aromatic substrates resulted from their treatment with LDA [92] or n-BuLi [93] Formylation of aromatic substrates resulted from their treatment with LDA [[92]92] or n-BuLi [[93]93] and, subsequently, DMF (Equation (81)). and, subsequently, DMFDMF (Equation(Equation (81)).(81)).

Graphene oxide reacted with DBU and DM to afford, in presence of trace of water, N-(3-(2- oxoazepan-1-yl)propyl)formamide or the corresponding acetamide (Equation (82)) [94].

15. RC=ON(CH2)Me Fragment N-Amidoalkylation of imidazoles and 1,2,3-triazoles with DM effectively arose under various experimental conditions (Equations (83) [95] and (84) [10]).

Molecules 2018, 23, x FOR PEER REVIEW 18 of 29

14. RC=O Fragment

Metal-catalyzed or CO2-mediated C–N and N–H bond metathesis reactions between primary or secondary amines and DM provided the transamidation products, that is formamides or acetamides (Equation (80)) [88–91].

MoleculesFormylation2018, 23, 1939 of aromatic substrates resulted from their treatment with LDA [92] or n-BuLi20 of[93] 31 and, subsequently, DMF (Equation (81)).

Graphene oxide reacted with DBU and DM to afford, in presence of trace of water, N-(3-(2--(3-(2- oxoazepan-1-yl)propyl)formamide oror thethe correspondingcorresponding acetamideacetamide (Equation(Equation (82))(82)) [[94].94].

2 15.R RC=OC=ON(CHN(CH 2)Me)Me Fragment Fragment N-Amidoalkylation of of imidazoles and 1,2,3-triazoles with with DM effectively arose under variousvarious experimentalMolecules 2018,, 23 conditions,, xx FORFOR PEERPEER (Equations REVIEWREVIEW (83)(83) [[95]95] andand (84)(84) [[10]).10]). 19 of 29

16. HC-ONMe2 Fragment 16.HC-ONMe 2 Fragment

Catalysis with Mo(CO)6 ofof thethe reductionreduction ofof DMFDMF withwith triethylsilanetriethylsilane affordedafforded aa Catalysis with Mo(CO)6 of the reduction of DMF with triethylsilane afforded a siloxymethylamine (Equationsiloxymethylamine (85)), which (Equation was used (85)), as a which Mannich was reagent used as [ 96a Mannich]. reagent [96].

17. RC andand O FragmentFragment Arynes, which are easily obtained from, for example 2-(trimethylsilyl)phenyl trifluoromethane- sulfonate, undergone a [2 + 2] cyclization with DM giving a benzoxetene and its isomer, the ortho- quinone methide (Scheme 3). Trapping of these intermediatesintermediates providesprovides variousvarious products,products, whichwhich contain the formyl or acetyl CH part and the O atom of DM (Equations (86) [19], (87) [20], (88) [21] and (89) [97]), or the HCNMe2 andand OO fragmentsfragments ofof DMFDMF (see(see SectionSection 18).18).

Scheme 3. AryneAryne formationformation andand reactionreaction withwith DM.DM.

Molecules 2018, 23, x FOR PEER REVIEW 19 of 29 Molecules 2018, 23, x FOR PEER REVIEW 19 of 29

16. HC-ONMe2 Fragment 16. HC-ONMe2 Fragment

Catalysis with Mo(CO)6 of the reduction of DMF with triethylsilane afforded a Catalysis with Mo(CO)6 of the reduction of DMF with triethylsilane afforded a siloxymethylamine (Equation (85)), which was used as a Mannich reagent [96]. siloxymethylamine (Equation (85)), which was used as a Mannich reagent [96].

Molecules 2018, 23, 1939 21 of 31

17.R RCC and andO O Fragment Fragment 17. RC and O Fragment Arynes, which are easily obtained from, for exam exampleple 2-(trimethylsilyl)phenyl trifluoromethane- trifluoromethane- Arynes, which are easily obtained from, for example 2-(trimethylsilyl)phenyl trifluoromethane- sulfonate, undergone a [2 + 2] cyclization with with DM DM giving giving a a benzoxetene benzoxetene and and its its isomer, isomer, the the ortho-- sulfonate, undergone a [2 + 2] cyclization with DM giving a benzoxetene and its isomer, the ortho- quinone methide (Scheme3 3).). TrappingTrapping ofof thesethese intermediatesintermediates providesprovides variousvarious products,products, whichwhich quinone methide (Scheme 3). Trapping of these intermediates provides various products, which contain thethe formylformyl oror acetyl acetyl CH CH part part and and the the O O atom atom of DMof DM (Equations (Equations (86) (86) [19 ],[19], (87) (87) [20], [20], (88) (88) [21] and[21] contain the formyl or acetyl CH part and the O atom of DM (Equations (86) [19], (87) [20], (88) [21] (89)and [(89)97]), [97]), or the or HCNMe the HCNMe2 and2 and O fragments O fragments of DMF of DMF (see Section(see Section 18). 18). and (89) [97]), or the HCNMe2 and O fragments of DMF (see Section 18).

Scheme 3. Aryne formation and reaction with DM. Scheme 3. Aryne formation and reaction with DM.

Molecules 2018, 23, x FOR PEER REVIEW 20 of 29 Molecules 2018, 23, x FOR PEER REVIEW 20 of 29

At 115 °C in wet toluene, the hexadehydro-Diels–Alder of tetraynes depicted in Equation (89) At 115 ◦°CC in wet toluene, the hexadehydro-Diels–Alderhexadehydro-Diels–Alder of tetraynes depicted in Equation (89) was in-situ followed by [2 + 2] cycloaddition reaction with DM leading to multifunctionalized was in-situ followed by [2[2 ++ 2] cycloadditioncycloaddition reaction with DM leadingleading toto multifunctionalizedmultifunctionalized salicylaldehydes and salicylketones [97]. salicylaldehydes and salicylketones [[97].97].

18. RCNMe2 and O Fragment 18.R RCNCNMeMe2 andand O FragmentFragment All atoms of DMF were inserted in the polyfunctionalized compounds produced from domino All atoms of DMF were inserted in the polyfunctionalized compounds produced from domino reactionsAll atomsinvolving of DMFformation were of insertedarynes, cycloaddition in the polyfunctionalized with DMF and compoundssubsequent trapping produced with from α- reactions involving formation of arynes, cycloaddition with DMF and subsequent trapping with α- dominochloro β reactions-diesters involving(Equation formation (90)) [22], of arynes, aroyl cycloadditioncyanides (Equation with DMF (91)) and subsequent[23] or diesters trapping of chloro β-diesters (Equation (90)) [22], aroyl cyanides (Equation (91)) [23] or diesters of acetylenedicarboxylic acid (Equation (92)) [24]. acetylenedicarboxylic acid (Equation (92)) [24].

Molecules 2018, 23, x FOR PEER REVIEW 20 of 29

At 115 °C in wet toluene, the hexadehydro-Diels–Alder of tetraynes depicted in Equation (89) was in-situ followed by [2 + 2] cycloaddition reaction with DM leading to multifunctionalized salicylaldehydes and salicylketones [97].

18. RCNMe2 and O Fragment Molecules 2018, 23, 1939 22 of 31 All atoms of DMF were inserted in the polyfunctionalized compounds produced from domino reactions involving formation of arynes, cycloaddition with DMF and subsequent trapping with α- withchloroα -chloroβ-diestersβ-diesters (Equation (Equation (90)) (90))[22], [22aroyl], aroyl cyanides cyanides (Equation (Equation (91)) (91)) [23] [23 ]or or diesters diesters ofof acetylenedicarboxylic acidacid (Equation(Equation (92))(92)) [[24].24].

Molecules 2018, 23, x FOR PEER REVIEW 21 of 29

19. HC=O and HC Fragment 19. H HC=OC=O andandH HCC Fragment Fragment Lithium thioanisole biscarbanion reacted with two molecules of DMF to afford benzo[bb]thiophene-2-carbaldehyde]thiophene-2-carbaldehyde (Equation(Equation (93))(93)) [[98].98].

20.H H and andN NMeMe2 Fragment The reactionreaction of of DMF DMF with with sodium sodium and subsequentand subseque additionnt addition of terminal of terminal activated activated alkynes affordedalkynes theafforded corresponding the corresponding hydroamination hydroamination compounds compounds (Equation (Equation (94)) [99]. (94)) [99].

21. H and C=ONMe2 Fragment 21.H H and and C=ON C=ONMeMe2 FragmentFragment

Semicarbazides have been synthetized from additions, mediated with (t-BuO)2 and catalytic Semicarbazides have been synthetizedsynthetized fromfrom additions,additions, mediatedmediated withwith ((tt-BuO)-BuO)22 and catalyticcatalytic amounts of both NaI and PhCOCl, of the H and CONMe2 moieties of DMF to the extremities of the amounts of both NaI andand PhCOCl,PhCOCl, ofof thethe HH andand CONMeCONMe22 moieties of DMF to the extremities of thethe N=N bondbond of of azoarenes azoarenes (Equation (Equation (95)) (95)) [100 ].[100]. The role The of role NaI andof NaI PhCOCl and isPhCOCl not clear is and, not furthermore, clear and, exchangefurthermore, of NaIexchange for imidazole of NaI ledfor toimidazole formylhydrazines led to formylhydrazines (Equation (96)) (Equation [100]. The (96)) corresponding [100]. The corresponding acetylhydrazine was not formed in DMAc (Equation (96)). The (t- acetylhydrazinecorresponding wasacetylhydrazine not formed in DMAcwas not (Equation formed (96)). in The DMAc (t-BuO) 2/NaI/PhCOCl/DMF(Equation (96)). The system (t- BuO)2/NaI/PhCOCl/DMF system led to the addition of H and CONMe2 to the N=C bond of N- benzylideneaniline but with low yield (Equation (97)) [100].

The Ru-catalyzed hydrocarbamoylative cyclization of 1,6-diynes proceeded in DMF to afford cyclic α,β,δ,γ-unsaturated amides (Equation (98)) [101–103].

Molecules 2018, 23, x FOR PEER REVIEW 21 of 29

19. HC=O and HC Fragment Lithium thioanisole biscarbanion reacted with two molecules of DMF to afford benzo[b]thiophene-2-carbaldehyde (Equation (93)) [98].

20. H and NMe2 Fragment The reaction of DMF with sodium and subsequent addition of terminal activated alkynes afforded the corresponding hydroamination compounds (Equation (94)) [99].

21. H and C=ONMe2 Fragment

Semicarbazides have been synthetized from additions, mediated with (t-BuO)2 and catalytic amounts of both NaI and PhCOCl, of the H and CONMe2 moieties of DMF to the extremities of the N=N bond of azoarenes (Equation (95)) [100]. The role of NaI and PhCOCl is not clear and, Molecules 2018, 23, 1939 23 of 31 furthermore, exchange of NaI for imidazole led to formylhydrazines (Equation (96)) [100]. The corresponding acetylhydrazine was not formed in DMAc (Equation (96)). The (t- ledBuO) to2 the/NaI/PhCOCl/DMF addition of H and system CONMe led2 to thethe N=Caddition bond of of HN -benzylideneanilineand CONMe2 to the but N=C with bond low of yield N- (Equationbenzylideneaniline (97)) [100 ].but with low yield (Equation (97)) [100].

The Ru-catalyzed hydrocarbamoylative cyclization of 1,6-diynes proceeded in DMF to afford The Ru-catalyzed hydrocarbamoylative cyclization of 1,6-diynes proceeded in DMF to afford cyclic α,β,δ,γ-unsaturated amides (Equation (98)) [101–103]. cyclicMoleculesα ,2018β,δ,,γ 23-unsaturated, x FOR PEER REVIEW amides (Equation (98)) [101–103]. 22 of 29

Molecules 2018, 23, x FOR PEER REVIEW 22 of 29

22. H, C=ONMe2 and NMe2 Fragment 22.H, C=ONMe 2 andNMe 2 Fragment 22. H, C=ONMe2 and NMe2 Fragment Re2(CO)8[μ-η2-C(H)=C(H)Bu](μ-H) undergone reaction with DMF leading to hexenyl/CONMe2 Re2(CO)8[µ-η -C(H)=C(H)Bu](µ-H) undergone reaction with DMF leading to hexenyl/CONMe2 and CO/HNMe2 8 2 exchange2 of ligands (Equation (99)) [104]. 2 and CO/HNMeRe (CO) [μ-2ηexchange-C(H)=C(H)Bu]( of ligandsμ-H) (Equation undergone (99)) reaction [104]. with DMF leading to hexenyl/CONMe and CO/HNMe2 exchange of ligands (Equation (99)) [104].

23. C=ONMe2 and CH Fragment 23. C=ONMe2 and CH Fragment Couplings between amidines, styrenes and fragments of two molecules of DMF in the presence Couplings between amidines, styrenes and fragments of two molecules of DMF in the presence of t-BuOOH and a PdII catalyst provided pyrimidine carboxamides (Equation (100)) [105]. DMAc may of t-BuOOH and a PdII catalyst provided pyrimidine carboxamides (Equation (100)) [105]. DMAc may also be the CH source as exemplified with the formation of the N,N-diethyl-2,4-diphenylpyrimidine- also be the CH source as exemplified with the formation of the N,N-diethyl-2,4-diphenylpyrimidine- 5-carboxamide when N,N-diethylformamide was the source of the amide moiety (Equation (101)). 5-carboxamide when N,N-diethylformamide was the source of the amide moiety (Equation (101)).

24.24. ReducingReducing or Stabilizing AgentAgent DMFDMF is a powerful reducingreducing agentagent of of metal metal salts, salts, hence hence its its use use for for the the preparation preparation of ofmetal metal colloidscolloids [106]. In wet DMF,DMF, PdClPdCl22 led led to to carbamic carbamic acid acid and and Pd(0) Pd(0) nanoparticles nanoparticles (Equation (Equation (102)) (102)) [107]. [107]. TheThe latterlatter have been associatedassociated withwith the the metal-organic metal-organic framework framework Cu Cu2(BDC)2(BDC)2(DABCO)2(DABCO) (BDC (BDC = 1,4- = 1,4- benzenedicarboxylate),benzenedicarboxylate), leadingleading toto aa catalyticcatalytic syst systemem with with high high activity activity and and recyclability recyclability for for the the

Molecules 2018, 23, x FOR PEER REVIEW 22 of 29

22. H, C=ONMe2 and NMe2 Fragment

Re2(CO)8[μ-η2-C(H)=C(H)Bu](μ-H) undergone reaction with DMF leading to hexenyl/CONMe2 and CO/HNMe2 exchange of ligands (Equation (99)) [104].

Molecules 2018, 23, 1939 24 of 31

23. C=ONMe2 andCH Fragment Couplings between amidines, styrenes and fragments of two molecules of DMF in the 23. C=ONMe2 and CH Fragment presence of t-BuOOH and a PdII catalyst provided pyrimidine carboxamides (Equation (100)) [105]. DMAcCouplings may also between be the amidines, CH source styrenes as exemplified and fragments with of the two formation molecules of of theDMFN ,inN -diethyl-2,4-the presence diphenylpyrimidine-5-carboxamideof t-BuOOH and a PdII catalyst provided when pyrimidineN,N-diethylformamide carboxamides was (Equation the source (100)) of the[105]. amide DMAc moiety may (Equationalso be the (101)). CH source as exemplified with the formation of the N,N-diethyl-2,4-diphenylpyrimidine- 5-carboxamide when N,N-diethylformamide was the source of the amide moiety (Equation (101)).

24. Reducing or Stabilizing Agent 24. Reducing or Stabilizing Agent DMF is a powerful reducing agent of metal salts, hence its use for the preparation of metal DMF is a powerful reducing agent of metal salts, hence its use for the preparation of metal colloidsMolecules 2018 [106, ].23, In x FOR wet PEER DMF, REVIEW PdCl2 led to carbamic acid and Pd(0) nanoparticles (Equation (102))23 [107 of 29]. colloids [106]. In wet DMF, PdCl2 led to carbamic acid and Pd(0) nanoparticles (Equation (102)) [107]. TheMolecules latter 2018 have, 23, beenx FOR associatedPEER REVIEW with the metal-organic framework Cu2(BDC)2(DABCO) (BDC23 = 1,4-of 29 benzenedicarboxylate),aerobicTheMolecules latter oxidation 2018 have, 23 been, xof FOR benzyl associated PEER leading alcoholsREVIEW to with a catalytic to the aldehydes metal-organic system [108] with and highframework Suzuki-Miyaura activity Cu and2(BDC) recyclability cross-coupling2(DABCO) for (BDC the reactions aerobic =23 1,4- of 29 oxidation[107].aerobicbenzenedicarboxylate), oxidation of benzyl of alcohols benzyl leading alcohols to aldehydes to ato catalytic aldehydes [108] andsyst [108] Suzuki-Miyauraem andwith Suzuki-Miyaura high activity cross-coupling and cross-coupling recyclability reactions reactions [for107 ].the [107].aerobic oxidation of benzyl alcohols to aldehydes [108] and Suzuki-Miyaura cross-coupling reactions [107].

In addition, DMF can act as stabilizing agent of metal colloids to afford effective and recyclable In addition, DMF can act as stabilizing agent of metal colloids to afford effective and recyclable catalysts,In addition, based for DMF examples: can act as stabilizing agent of metal colloids to afford effective and recyclable catalysts,In basedaddition, for examples:DMF can act as stabilizing agent of metal colloids to afford effective and recyclable -catalysts, on iron based for thefor hydrosilylationexamples: of alkenes (Equation (103)) [109], catalysts, based for examples: - - onon ironiron forfor thethe hydrosilylationhydrosilylation ofof alkenesalkenes (Equation(Equation (103))(103)) [[109],109], - on iron for the hydrosilylation of alkenes (Equation (103)) [109],

- on palladium for the synthesis of 2,3-disubstituted indoles from 2-halooanilines and alkynes

- (Equationon palladium (104)) for [110], the synthesis of 2,3-disubstituted indoles from 2-halooanilines and alkynes - on palladium for the synthesis of 2,3-disubstituted indoles from 2-halooanilines and alkynes - (Equationon palladium (104)) for[110], the synthesis of 2,3-disubstituted indoles from 2-halooanilines and alkynes (Equation(Equation (104)) (104)) [110 [110],],

- on copper for Sonogashira–Hagihara cross-coupling reactions (Equation (105)) [111],

- on copper for Sonogashira–Hagihara cross-coupling reactions (Equation (105)) [111], - on copper for Sonogashira–Hagihara cross-coupling reactions (Equation (105)) [111],

- on iridium for methylation of alcohols (Equation (106)) and amines (Equation (107)), using

- methanolon iridium as forthe C1methylation source [112]. of alcohols (Equation (106)) and amines (Equation (107)), using - methanolon iridium as the for C1 methylation source [112]. of alcohols (Equation (106)) and amines (Equation (107)), using methanol as the C1 source [112].

Thermal decomposition of DMF leads to CO, which reacts with water under CuFe 2O4 catalysis

to produceThermal hydrogen decomposition [113]. In of the DMF presence leads ofto 2-nitroanilines,CO, which reacts this with water water gas under shift reactionCuFe2O 4was catalysis part ofto aproduce dominoThermal hydrogen reaction decomposition [113].involving In theof DMFthe presence reduction leads of to 2-nitroanilines, CO,of thewhich nitro reacts groupthis with water followed water gas shiftunder by reaction cyclisationCuFe2O was4 catalysis intopart benzimidazolesofto a producedomino hydrogenreaction using a CHinvolving[113]. from In thethe the presenceNMe reduction2 of DMFof 2-nitroanilines,of (Equationthe nitro (108))group this [113].water followed Such gas shift cyclisationby cyclisationreaction is wasabove into part of a domino reaction involving the reduction of the nitro group followed by cyclisation into documentedbenzimidazoles under using different a CH fromexperiment the NMeal conditions2 of DMF (Equation (Equation (108)) (18)) [50].[113]. Such cyclisation is above documentedbenzimidazoles under using different a CH experiment from the NMeal conditions2 of DMF (Equation(Equation (18))(108)) [50]. [113]. Such cyclisation is above documented under different experimental conditions (Equation (18)) [50].

Molecules 2018, 23, x FOR PEER REVIEW 23 of 29 Molecules 2018, 23, x FOR PEER REVIEW 23 of 29 Moleculesaerobic 2018 oxidation, 23, x FOR ofPEER benzyl REVIEW alcohols to aldehydes [108] and Suzuki-Miyaura cross-coupling reactions23 of 29 aerobic[107]. oxidation of benzyl alcohols to aldehydes [108] and Suzuki-Miyaura cross-coupling reactions aerobic[107]. oxidation of benzyl alcohols to aldehydes [108] and Suzuki-Miyaura cross-coupling reactions [107].

In addition, DMF can act as stabilizing agent of metal colloids to afford effective and recyclable catalysts,In addition, based for DMF examples: can act as stabilizing agent of metal colloids to afford effective and recyclable catalysts,In addition, based DMF for examples: can act as stabilizing agent of metal colloids to afford effective and recyclable catalysts,- on based iron for for the examples: hydrosilylation of alkenes (Equation (103)) [109], - on iron for the hydrosilylation of alkenes (Equation (103)) [109], - on iron for the hydrosilylation of alkenes (Equation (103)) [109],

- on palladium for the synthesis of 2,3-disubstituted indoles from 2-halooanilines and alkynes - on(Equation palladium (104)) for [110], the synthesis of 2,3-disubstituted indoles from 2-halooanilines and alkynes - on (Equationpalladium (104)) for the [110], synthesis of 2,3-disubstituted indoles from 2-halooanilines and alkynes (Equation (104)) [110],

Molecules 2018, 23, 1939 25 of 31

- - onon copper copper for for Sonogashira–Hagihara Sonogashira–Hagihara cross-coupling cross-coupling reactions reactions (Equation (Equation (105)) (105)) [111 [111],], - on copper for Sonogashira–Hagihara cross-coupling reactions (Equation (105)) [111], - on copper for Sonogashira–Hagihara cross-coupling reactions (Equation (105)) [111],

- on iridium for methylation of alcohols (Equation (106)) and amines (Equation (107)), using - - on iridium for methylation of alcohols (Equation (106)) and amines (Equation (107)), using onmethanol iridium as for the methylationC1 source [112]. of alcohols (Equation (106)) and amines (Equation (107)), using - onmethanol methanoliridium as foras the themethylation C1 C1 source source [112 of[112].]. alcohols (Equation (106)) and amines (Equation (107)), using methanol as the C1 source [112].

Thermal decomposition of DMF leads to CO, which reacts with water under CuFe2O4 catalysis to produceThermal hydrogen decomposition [113]. In of the DMF presence leads toof CO,2-nitroanilines, which reacts this with water water gas under shift CuFereaction2O4 wascatalysis part Thermal decompositiondecomposition ofof DMF DMF leads leads to to CO, CO, which which reacts reacts with with water water under under CuFe CuFeO2Ocatalysis4 catalysis to toof producea domino hydrogen reaction [113]. involving In the thepresence reduction of 2-nitroanilines, of the nitro thisgroup water followed gas shift by 2reaction cyclisation4 was partinto produceto ofproduce a domino hydrogen hydrogen reaction [113 [113].]. Ininvolving theIn the presence presence the ofreduction 2-nitroanilines, of 2-nitroanilines, of the thisnitro this water group water gas followedgas shift shift reaction reactionby cyclisation was was part part of into a benzimidazoles using a CH from the NMe2 of DMF (Equation (108)) [113]. Such cyclisation is above dominoof a domino reaction reaction involving involving the reduction the reduction of the2 nitro of group the nitro followed group by cyclisationfollowed intoby cyclisation benzimidazoles into benzimidazolesdocumented under using different a CH from experiment the NMeal conditions of DMF (Equation (Equation (108)) (18)) [113].[50]. Such cyclisation is above usingbenzimidazolesdocumented a CH from underusing the NMedifferenta CH2 fromof DMFexperiment the (EquationNMe2al of conditions DMF (108)) (Equation [113 (Equation]. Such (108)) cyclisation(18)) [113]. [50]. Such is abovecyclisation documented is above underdocumented different under experimental different experiment conditions (Equational conditions (18)) (Equation [50]. (18)) [50].

25. Conclusions This minireview highlights recent uses of DMF and DMAc as sources of building blocks in various reactions of the organic synthesis. We assume that new uses of these multipurpose reagents will be reported.

Author Contributions: J. Muzart collected the literature references. J. Muzart and J. Le Bras contributed to the manuscript writing. Funding: This research received no external funding. Conflicts of Interest: The authors declare no conflicts of interest.

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