DOCSLIB.ORG

A New Reagent for the Oxidation of Hydrazones to Diazo Compounds Simon M

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A New Reagent for the Oxidation of Hydrazones to Diazo Compounds Simon M DOI: 10.1002/chem.201304656 Full Paper & Synthetic Methods Potassium N-Iodo p-Toluenesulfonamide (TsNIK, Iodamine-T): A New Reagent for the Oxidation of Hydrazones to Diazo Compounds Simon M. Nicolle and Christopher J. Moody*[a] Abstract: A new reagent for the oxidation of hydrazones to good yield and in high purity after a simple extractive work- diazo compounds is described. N-Iodo p-toluenesulfonamide up. a-Diazoesters were also obtained in high yield from the (TsNIK, iodamine-T) allows the preparation of a-diazoesters, corresponding ketones through a one-pot process of hydra- a-diazoamides, a-diazoketones and a-diazophosphonates in zone formation/oxidation. Introduction fonyl azide[12] have been used. Possible alternative methods are the thermal decomposition of tosylhydrazones in the pres- Diazo compounds are useful and versatile synthetic intermedi- ence of a base (Bamford–Stevens reaction),[7,13,14] or the dehy- ates and their rich chemistry has attracted great interest since drogenation of simple hydrazones. The latter has been classi- the first synthesis of ethyl diazoacetate by Curtius in 1883.[1] cally carried out using heavy metal based reagents, such as [15–17] [18,19] [20] [21,22] One of their main features is the generation of carbenes or HgO, Ag2O, Pb(OAc)4, MnO2, alumina-supported [23] [24] [25] [21] [26] metal carbenoids, reactive intermediates that undergo a wide KMnO4, Ni2O3, CrO2, but also Ca(OCl)2, Oxone, I2/per- range of synthetically useful reactions including CÀH and XÀH acid[27] and hypervalent iodine reagents.[28–30] More recently, ac- insertion reaction (X=N, O, S, P, Si),[2,3] cyclopropanation reac- tivated DMSO[31] and NaOCl/TEMPO[32] have also been em- [4,5] tions and ylide formation. With conservation of the diazo ployed. However, the most widely used methods (HgO, MnO2, moiety, they also react as 1,3-dipoles in cycloaddition reactions Pb(OAc)4 and Ag2O), despite the convenience of some proto- to give heterocycles.[6] cols for lab-scale preparations, do not offer satisfactory condi- The numerous routes available for the preparation of diazo tions in terms of waste production and/or toxicity. Moreover, compounds reflect not only over a century of research, but isolation of the diazo compound from the reaction media is also the range of reactivity encountered amongst the mem- often problematic owing to the sensitivity of the less stabilized bers of this class. In fact, few other types of compounds pres- compounds toward, for instance, purification by column chro- ent a stability trend that is so substitution dependent: from matography (as is the case for diphenyldiazomethane). In sev- toxic and highly reactive diazoalkanes to well-behaved, bench- eral examples, the efficiency of the oxidation process is only stable diazocarbonyl compounds, the stability of diazo com- determined by acid decomposition of the diazo compound pounds is strongly related to the substitution on the diazo- and measurement of the quantity of evolved nitrogen[20,27,31] or bearing carbon atom.[7,8] Stabilised diazo compounds are usual- isolation of the ester produced (decomposition by a carboxylic ly synthesized by the diazo-transfer method, using sulfonyl acid),[18, 23–26,32] neither of which are worthwhile if one requires azides as the transfer reagent.[9] The main drawback of this the diazo compound itself for further synthetic transforma- method is the hazard associated with the use of potentially ex- tions. Notwithstanding the aforementioned examples, we set plosive sulfonyl azides, such as p-toluenesulfonyl azide and out to develop a new, user-friendly method for the dehydro- mesyl azide,[10] although safer alternative reagents such as p- genation of hydrazones that offers a broad substrate scope dodecylbenzenesulfonyl azide[11] and p-acetamidobenzenesul- and a simple purification of the diazo compound. We now report our results. [a] S. M. Nicolle, Prof. Dr. C. J. Moody School of Chemistry Results and Discussion University of Nottingham, Nottingham NG7 2RD (UK) Fax: (+ 44)115-951-3564 With the aforementioned objectives in mind, we began investi- E-mail: [email protected] gating iodine-based oxidants. As noted by Barton et al., the Supporting information for this article is available on the WWW under oxidation of simple hydrazones with molecular iodine leads, in http://dx.doi.org/10.1002/chem.201304656. the presence of a base, to iodinated species by the intermedia- 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. cy of the diazo compound, or, as in the case of benzophenone This is an open access article under the terms of the Creative Commons At- tribution License, which permits use, distribution and reproduction in any hydrazone (1), to the corresponding diazo compound, diphen- medium, provided the original work is properly cited. yldiazomethane (2).[33,34] Other methods, based on the combi- Chem. Eur. J. 2014, 20, 4420 – 4425 4420 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Full Paper nation of sub-stoichiometric iodine source and a stoichiometric temperature (Table 1, entry 4). Diphenyldiazomethane (2)was oxidant, suggest the involvement of an iodine-based oxidant obtained in good yield under these conditions using a slight in these processes.[27,35] Using benzophenone hydrazone (1)to excess of oxidant, while benzophenone azine 3 was produced investigate oxidation conditions, we found that the use of as a side product. The use of a solution of potassium hydrox- N-iodosuccinimide at À788C, together with one equivalent of ide (1m) in a mixture with THF (ratio 4:1) led to a comparable base, led to diphenyldiazomethane (2) in reasonable yield yield but improved the purity of the final product obtained (Table 1, entries 1 to 3) but accompanied by up to 24% of ben- after a simple work-up (Table 1, entry 5). The reduction of TsNIK produces potassium iodide, which is in turn susceptible to oxidation to iodine. In the presence of potassium hydroxide, Table 1. Oxidation of benzophenone hydrazone using TsNIK and related iodine gives the unstable hypoiodite KOI, which disproportion- reagents. ates at appreciable rates to give potassium iodide and iodate. In another experiment, we found that an excess of freshly pre- pared hypoiodite aqueous solution led to partial oxidation of a solution of hydrazone 1 in ether (Table 1, entry 6). Unfortu- nately, the yield was low, likely owing to the rapid decay of po- [a] Entry Conditions Yield[%] tassium hypoiodite and to inefficient mass transfers. In this 123 regard, the potassium salt TsNIK might act as a stable hypoio- 1 NIS (1.0 equiv), TMG (1.0 equiv), THF À78 8Cnd7111dite equivalent. 2 NIS (1.0 equiv), DBU (1.0 equiv), THF À788Cnd6424 The reaction can also be successfully carried out in dry dime- 3 NIS (1.0 equiv), NEt3 (1.0 equiv), THF À788Cnd817 4 TsNIK (1.1 equiv), THF/H2O (23:2), rt 4 84 3 thylformamide, giving 88 % conversion of the hydrazone 1 into 5 TsNIK (1.1 equiv), THF/KOH (4:1), rt 4 94 <1 diazo compound 2 (Table 1, entry 7). Reaction in dry THF was 6 aqueous “KOI” (3 equiv), H2O/Et2O, rt 79 20 nd possible by addition of 18-crown-6 (0.1 equiv) to increase solu- 7 TsNIK (1.1 equiv), DMF, rt 11 88 nd 8 TsNIK (1.05 equiv), THF, 18-crown-6 (0.1 equiv), rt 6 90 2 bility of TsNIK (Table 1, entry 8). Reactions carried out in metha- 9 TsNIK (1.1 equiv), MeOH/H2O (49:1), rt 53 27 nd nol/water led to poor conversions (Table 1, entry 9). Using the 10 TsNClNa (1.1 equiv), THF, 18-crown-6 (0.1 equiv), rt 33 25 42 THF/KOH (1m) solvent system, the sulfonamide resulting from 11 TsNClNa (1.1 equiv), DMF, 08Ctort 74 21 4 the reduction of TsNIK was easily and quantitatively removed [a] Yields determined by analysis of the product isolated after an aqueous from the reaction media by washing with a solution of potassi- work-up. nd: not detected. NIS=N-iodo succinimide, DBU =1,8- um hydroxide (1m) and extraction in diethyl ether. Moreover, diazabicyclo[5.4.0]undec-7-ene, TMG=1,1,3,3-tetramethylguanidine. the product extracted in the organic phase was found to be of satisfactory purity (96 % by 1H NMR analysis), and further purifi- cation was not carried out. p-Toluenesulfonamide, the precur- zophenone azine 3. Based on these results, we sought alterna- sor to TsNIK, was recovered from the aqueous phase by an tive methods involving a mild iodinating species capable of acidification/extraction sequence, and in principle can be recy- neutralizing the two proton equivalents generated during the cled by treatment with I2/KI/KOH or KI/bleach. In contrast, the oxidation of the hydrazone, as the less stabilized diazo com- use of TsNClNa (chloramine-T) for hydrazine oxidation proved pounds readily decompose in the presence of acid. The rarely unsatisfactory under similar conditions (Table 1, entries 10 and investigated N-iodo potassium p-toluene-sulfonamide salt 4 11). (TsNIK, also known as iodamine-T), potassium salt and iodinat- Based on these encouraging results and in order to establish ed counterpart of the well-established chloramine-T, was se- the scope of this oxidation, we set out to prepare a number of lected on the basis of these criteria. This reagent is convenient- hydrazones from diverse ketone precursors. Various a-ketoest- ly and rapidly prepared from inexpensive p-toluenesulfon- er and a-ketoamide hydrazones were obtained by condensa- amide in multi-gram quantity and good yield (74 %) by treat- tion of either commercially or readily available a-keto-esters or ment with iodine in a mixture of aqueous KI and KOH, and -amides with hydrazine hydrate in presence of a weak Brønst- simply collected by filtration.[36] Alternatively, because iodine is ed acid, as previously reported (Table 2).[38,39] The reaction was considered as an “at risk” element,[37] we developed a second carried out in methanol/water using acetic acid (conditions a, protocol using KI and bleach solution to generate iodine, a pro- Table 2) or in THF using benzoic acid (conditions b, Table 2), tocol that gave the reagent in 44 % yield (Scheme 1).
Load more

Recommended publications
  • Carbene and Nitrene Transfer Reactions Joseph B
    University of South Florida Scholar Commons Graduate Theses and Dissertations Graduate School 11-19-2014 Co(II) Based Metalloradical Catalysis: Carbene and Nitrene Transfer Reactions Joseph B. Gill University of South Florida, [email protected] Follow this and additional works at: https://scholarcommons.usf.edu/etd Part of the Organic Chemistry Commons Scholar Commons Citation Gill, Joseph B., "Co(II) Based Metalloradical Catalysis: Carbene and Nitrene Transfer Reactions" (2014). Graduate Theses and Dissertations. https://scholarcommons.usf.edu/etd/5484 This Dissertation is brought to you for free and open access by the Graduate School at Scholar Commons. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. Co(II) Based Metalloradical Catalysis: Carbene and Nitrene Transfer Reactions by Joseph B. Gill A dissertation in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Chemistry College of Arts and Sciences University of South Florida Major Professor: X. Peter Zhang, Ph.D. Jon Antilla, Ph.D Jianfeng Cai, Ph.D. Edward Turos, Ph.D. Date of Approval: November 19, 2014 Keywords: cyclopropanation, diazoacetate, azide, porphyrin, cobalt. Copyright © 2014, Joseph B. Gill Dedication I dedicate this work to my parents: Larry and Karen, siblings: Jason and Jessica, and my partner: Darnell, for their constant support. Without all of you I would never have made it through this journey. Thank you. Acknowledgments I would like to thank my advisor, Professor X. Peter Zhang, for his support and guidance throughout my time working with him.
    [Show full text]
  • Organic Synthesis: New Vistas in the Brazilian Landscape
    Anais da Academia Brasileira de Ciências (2018) 90(1 Suppl. 1): 895-941 (Annals of the Brazilian Academy of Sciences) Printed version ISSN 0001-3765 / Online version ISSN 1678-2690 http://dx.doi.org/10.1590/0001-3765201820170564 www.scielo.br/aabc | www.fb.com/aabcjournal Organic Synthesis: New Vistas in the Brazilian Landscape RONALDO A. PILLI and FRANCISCO F. DE ASSIS Instituto de Química, UNICAMP, Rua José de Castro, s/n, 13083-970 Campinas, SP, Brazil Manuscript received on September 11, 2017; accepted for publication on December 29, 2017 ABSTRACT In this overview, we present our analysis of the future of organic synthesis in Brazil, a highly innovative and strategic area of research which underpins our social and economical progress. Several different topics (automation, catalysis, green chemistry, scalability, methodological studies and total syntheses) were considered to hold promise for the future advance of chemical sciences in Brazil. In order to put it in perspective, contributions from Brazilian laboratories were selected by the citations received and importance for the field and were benchmarked against some of the most important results disclosed by authors worldwide. The picture that emerged reveals a thriving area of research, with new generations of well-trained and productive chemists engaged particularly in the areas of green chemistry and catalysis. In order to fulfill the promise of delivering more efficient and sustainable processes, an integration of the academic and industrial research agendas is to be expected. On the other hand, academic research in automation of chemical processes, a well established topic of investigation in industrial settings, has just recently began in Brazil and more academic laboratories are lining up to contribute.
    [Show full text]
  • And Intermolecular Cyclopropanation by Co(II)- Based Metalloradical Catalysis Xue Xu University of South Florida, [email protected]
    University of South Florida Scholar Commons Graduate Theses and Dissertations Graduate School January 2012 Asymmetric Intra- and Intermolecular Cyclopropanation by Co(II)- Based Metalloradical Catalysis Xue Xu University of South Florida, [email protected] Follow this and additional works at: http://scholarcommons.usf.edu/etd Part of the American Studies Commons, and the Organic Chemistry Commons Scholar Commons Citation Xu, Xue, "Asymmetric Intra- and Intermolecular Cyclopropanation by Co(II)- Based Metalloradical Catalysis" (2012). Graduate Theses and Dissertations. http://scholarcommons.usf.edu/etd/4262 This Dissertation is brought to you for free and open access by the Graduate School at Scholar Commons. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. Asymmetric Intra- and Intermolecular Cyclopropanation by Co(II)- Based Metalloradical Catalysis by Xue(Snow) Xu A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Chemistry College of Arts and Sciences University of South Florida Major Professor: X. Peter Zhang, Ph.D. Jon Antilla, Ph.D. Mark L. McLaughlin, Ph.D. Wayne Guida, Ph.D. Date of Defense: June 20th, 2012 Keywords: cobalt, porphyrin, catalysis, cyclopropanation, carbene, diazo Copyright © 2012, Xue Xu DEDICATION I dedicate this dissertation to my parents and my husband, without their caring support, it would not have been possible. ACKNOWLEGEMENTS I need to begin with thanking Dr. Peter Zhang for his continuous guidance and support over the last 5 and half years. Especially for encouraging me to achieving my potential as a researcher and setting an example of dedication to science that is admirable.
    [Show full text]
  • Recent Advances on Mechanistic Studies on C–H Activation
    Open Chem., 2018; 16: 1001–1058 Review Article Open Access Daniel Gallego*, Edwin A. Baquero Recent Advances on Mechanistic Studies on C–H Activation Catalyzed by Base Metals https:// doi.org/10.1515/chem-2018-0102 received March 26, 2018; accepted June 3, 2018. 1Introduction Abstract: During the last ten years, base metals have Application in organic synthesis of transition metal- become very attractive to the organometallic and catalytic catalyzed cross coupling reactions has been positioned community on activation of C-H bonds for their catalytic as one of the most important breakthroughs during the functionalization. In contrast to the statement that new millennia. The seminal works based on Pd–catalysts base metals differ on their mode of action most of the in the 70’s by Heck, Noyori and Suzuki set a new frontier manuscripts mistakenly rely on well-studied mechanisms between homogeneous catalysis and synthetic organic for precious metals while proposing plausible chemistry [1-5]. Late transition metals, mostly the precious mechanisms. Consequently, few literature examples metals, stand as the most versatile catalytic systems for a are found where a thorough mechanistic investigation variety of functionalization reactions demonstrating their have been conducted with strong support either by robustness in several applications in organic synthesis [6- theoretical calculations or experimentation. Therefore, 12]. Owing to the common interest in the catalysts mode we consider of highly scientific interest reviewing the of action by many research groups, nowadays we have a last advances on mechanistic studies on Fe, Co and Mn wide understanding of the mechanistic aspects of precious on C-H functionalization in order to get a deep insight on metal-catalyzed reactions.
    [Show full text]
  • Experimental and Ab Initio Studies of Formation, Thermolysis, and Molecular and Electronic Structures of 3,6-Diphenyl-1-Propanesulfenimido-1,2,4,5-Tetrazine
    J. Am. Chem. Soc. 2000, 122, 2087-2095 2087 Nucleophile-Induced Intramolecular Dipole 1,5-Transfer and 1,6-Cyclization: Experimental and ab Initio Studies of Formation, Thermolysis, and Molecular and Electronic Structures of 3,6-Diphenyl-1-propanesulfenimido-1,2,4,5-tetrazine Piotr Kaszynski*,† and Victor G. Young, Jr.‡ Contribution from the Organic Materials Research Group, Department of Chemistry, Vanderbilt UniVersity, NashVille, Tennessee 37235, and X-ray Crystallographic Laboratory, Department of Chemistry, UniVersity of Minnesota, Twin Cities, Minnesota 55455 ReceiVed NoVember 1, 1999 Abstract: Reaction of dichlorobenzaldazine (2) with sodium azide followed by 1-propanethiol/Et3N furnished tetrazine ylide 1 as the main product. The structure of this unprecedented ylide was confirmed with single- crystal X-ray analysis [C17H17N5S, monoclinic P21/na) 6.8294(4) Å, b ) 13.6781(9) Å, c ) 17.5898(12) Å, â ) 90.666(1)°, Z ) 4] and favorably compared with the results of ab initio calculations. The mechanisms of formation of the ylide and its thermal decomposition to 2,5-diphenyltetrazine (5) were investigated using ab initio methods and correlated with the experimental observations. The results suggest that formation of 1 involves intramolecular cyclization of a nitrile imine and thermolysis of 1 might generate a sulfenylnitrene. The formation of 1 is considered to be the first example of a potentially more general reaction. Introduction Results and Discussion Intramolecular reactions of 1,3-dipoles provide one of the Synthesis of 1. 3,6-Diphenyl-1-propanesulfenimido-1,2,4,5- most versatile ways to construct heterocyclic rings.1 Among tetrazine (1) was obtained in a one-pot reaction.
    [Show full text]
  • Therapeutic Review Exploring Antimicrobial Potential of Hydrazones As Promising Lead
    Available online a t www.derpharmachemica.com Scholars Research Library Der Pharma Chemica, 2011, 3(1):250-268 (http://derpharmachemica.com/archive.html) ISSN 0975-413X CODEN (USA): PCHHAX Therapeutic Review Exploring Antimicrobial Potential of Hydrazones as Promising Lead Goldie Uppal, Suman Bala*, Sunil Kamboj and Minaxi Saini M.M. College of Pharmacy, Maharishi Markandeshwar University, Ambala, Haryana, India ______________________________________________________________________________ ABSTRACT This review includes detailed study of structures of various hydrazones synthesized and evaluated for their antimicrobial activity. Hydrazone is a class of organic compounds with structure R 1R2C=NNH 2. Hydrazones containing an azomethine -NHN=CH- proton which leads to an important class of compounds for new drug development. Hydrazones are present in many of the bioactive heterocyclic compounds that are of very important use because of their various biological and clinical applications. Therefore, many researchers have synthesized these compounds as target structures and evaluated their antimicrobial activities. These observations have been guiding for the development of new hydrazones that possess varied biological activities. Key Words: Hydrazones, Hydrazide, Antifungal Activity, Antimicrobial Activity. ______________________________________________________________________________ INTRODUCTION The need to design new compounds to deal with the resistant strains has become one of the most important areas of research today. Hydrazone is a versatile moiety that exhibits a wide variety of biological activities. A hydrazone is a class of organic compounds with the structure R1R2C=NNH 2. Hydrazones are basically related to ketones and aldehydes. Hydrazones are formed by the replacement of the oxygen of carbonyl compounds with the -NNH 2 functional group. Hydrazones act as reactants in many important reactions e.g.
    [Show full text]
  • Diazo Chemistry Baran Group Meeting Kevin Rodriguez 6/8/19
    Diazo Chemistry Baran Group Meeting Kevin Rodriguez 6/8/19 1. History and Introduction Silberrad and Roy discover First reported Ronald Diegle, scientist Both Fe and Ru Hans Von Pechmann Cu dust decomposes death from CH N at Sepracor Canda dies began widespread adoption Theodore Curtius discovers CH N 2 2 O discovers diazoacetic acid 2 2 ethyldiazoacetate exposure from TMSCHN2 exposure O2N N2 N 1858 NO2 1892 1898 1943 1973 2009 2011 2 1883 1894 1906 1949 2008 2010 Peter Griess William Will and German Hans Von Pechmann Gilman and Jones Rhodium carboxylates were Iridium-Salen complexes Gold rush begins discovers scientists begin investigating serendipitously discovers report deca-gram found to catalyze the also found to enable DDNP DDNP as explosive polyethylene synthesis of CF3CHN2 cyclopropanation of olefins with cyclopropanations from CH2N2 ethyldiazoacetate Definition: Group Meeting includes: N N - Introduction to different classes of diazo compounds A diazo compound is an organic compound bearing two nitrogen N N - Preparation and synthesis of diazoalkanes and stabilized derivatives atoms and neutrally charged. - Non-metal-mediated reactions R R R R - Transition metal-mediated reactions The term "diazo" is loosely used throughout the literature. For example, diazonium salts and azo - Common trends in C-H activation should be not be used when describing a diazo motif. Only the ylide form (vide supra) bears the - Towards heterocyclic chemistry proper IUPAC name. - Naturally occuring natural products Stability: Group Meeting does not include: In general, due to the tendency of these to liberate N2, care should be taken when preparing and - Extensive focus on any topic handling most diazo compounds.
    [Show full text]
  • Chemical Redox Agents for Organometallic Chemistry
    Chem. Rev. 1996, 96, 877−910 877 Chemical Redox Agents for Organometallic Chemistry Neil G. Connelly*,† and William E. Geiger*,‡ School of Chemistry, University of Bristol, U.K., and Department of Chemistry, University of Vermont, Burlington, Vermont 05405-0125 Received October 3, 1995 (Revised Manuscript Received January 9, 1996) Contents I. Introduction 877 A. Scope of the Review 877 B. Benefits of Redox Agents: Comparison with 878 Electrochemical Methods 1. Advantages of Chemical Redox Agents 878 2. Disadvantages of Chemical Redox Agents 879 C. Potentials in Nonaqueous Solvents 879 D. Reversible vs Irreversible ET Reagents 879 E. Categorization of Reagent Strength 881 II. Oxidants 881 A. Inorganic 881 1. Metal and Metal Complex Oxidants 881 2. Main Group Oxidants 887 B. Organic 891 The authors (Bill Geiger, left; Neil Connelly, right) have been at the forefront of organometallic electrochemistry for more than 20 years and have had 1. Radical Cations 891 a long-standing and fruitful collaboration. 2. Carbocations 893 3. Cyanocarbons and Related Electron-Rich 894 Neil Connelly took his B.Sc. (1966) and Ph.D. (1969, under the direction Compounds of Jon McCleverty) degrees at the University of Sheffield, U.K. Post- 4. Quinones 895 doctoral work at the Universities of Wisconsin (with Lawrence F. Dahl) 5. Other Organic Oxidants 896 and Cambridge (with Brian Johnson and Jack Lewis) was followed by an appointment at the University of Bristol (Lectureship, 1971; D.Sc. degree, III. Reductants 896 1973; Readership 1975). His research interests are centered on synthetic A. Inorganic 896 and structural studies of redox-active organometallic and coordination 1.
    [Show full text]
  • Bond Forming Reactions Involving Isocyanides at Diiron Complexes
    inorganics Review Bond Forming Reactions Involving Isocyanides at Diiron Complexes Rita Mazzoni 1 , Fabio Marchetti 2,*, Andrea Cingolani 1 and Valerio Zanotti 1,* 1 Dipartimento di Chimica Industriale “Toso Montanari”, University of Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy; [email protected] (R.M.); [email protected] (A.C.) 2 Dipartimento di Chimica e Chimica Industriale, University of Pisa, Via G. Moruzzi 13, I-56124 Pisa, Italy * Correspondence: [email protected] (F.M.); [email protected] (V.Z.); Tel.: +39-051-209-3694 (V.Z.) Received: 28 January 2019; Accepted: 14 February 2019; Published: 26 February 2019 Abstract: The versatility of isocyanides (CNR) in organic chemistry has been tremendously enhanced by continuous advancement in transition metal catalysis. On the other hand, the urgent need for new and more sustainable synthetic strategies based on abundant and environmental-friendly metals are shifting the focus towards iron-assisted or iron-catalyzed reactions. Diiron complexes, taking advantage of peculiar activation modes and reaction profiles associated with multisite coordination, have the potential to compensate the lower activity of Fe compared to other transition metals, in order to activate CNR ligands. A number of reactions reported in the literature shows that diiron organometallic complexes can effectively assist and promote most of the “classic” isocyanide transformations, including CNR conversion into carbyne and carbene ligands, CNR insertion, and coupling reactions with other active molecular fragments in a cascade sequence. The aim is to evidence the potential offered by diiron coordination of isocyanides for the development of new and more sustainable synthetic strategies for the construction of complex molecular architectures.
    [Show full text]
  • Cyclopropanation Chem 115
    Myers Cyclopropanation Chem 115 Reviews: • Bonding Orbitals in Cyclopropane (Walsh Model): Roy, M.-N.; Lindsay, V. N. G.; Charette, A. B. Stereoselective Synthesis: Reactions of Carbon– Carbon Double Bonds (Science of Synthesis); de Vries, J. G., Ed.; Thieme: Stuttgart, 2011, Vol 1.; 731–817. Lebel, H.; Marcoux, J.-F.; Molinaro, C.; Charette, A. B. Chem. Rev. 2003, 103, 977–1050. Davies, H. M. L.; Beckwith, R. E. J. Chem. Rev. 2003, 103, 2861–2903. Li, A-H.; Dai, L. X.; Aggarwal, V. K. Chem. Rev. 1997, 97, 2341–2372. eS (") eA (") • Applications of Cyclopropanes in Synthesis Carson, C. A.; Kerr, M. A. Chem. Soc. Rev. 2009, 38, 3051–3060. Reissig, H.-U.; Zimmer, R. Chem. Rev. 2003, 103, 1151–1196. Gnad, F.; Reiser, O. Chem. Rev. 2003, 103, 1603–1624. • Cyclopropane Biosynthesis ! Thibodeaux, C. J.; Chang, W.-c.; Liu, H.-w. Chem. Rev. 2012, 112, 1681–1709. de Meijere, A. Angew. Chem. Int. Ed. 1979, 18, 809–886. General Strategies for Cyclopropanation: Introduction • via carbenoids "MCH2X" H HH H H H • via carbenes generated by decomposition of diazo compounds H H H H H H RCHN2 • Cyclopropanes are stable but highly strained compounds (ring strain ~29 kcal/mol). R • via Michael addition and ring closure • C–C bond angles = 60º (vs 109.5º for normal Csp3–Csp3 bonds). • Substituents on cyclopropanes are eclipsed. H–C–H angle is ~120º. As a result, the C–H bonds RCH–LG have higher s character compared to normal sp3 bonds. EWG EWG EWG LG R • Because of their inherent strain, the reactivity of cyclopropanes is more closely analogous to that of alkenes than that of alkanes.
    [Show full text]
  • Recent Advances in the Iron-Catalyzed Cycloaddition Reactions
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Springer - Publisher Connector Review SPECIAL TOPIC July 2012 Vol.57 No.19: 23382351 Iron Catalysis in Synthetic Organic Chemistry doi: 10.1007/s11434-012-5141-z Recent advances in the iron-catalyzed cycloaddition reactions WANG ChunXiang & WAN BoShun* Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China Received December 19, 2011; accepted February 13, 2012; published online April 26, 2012 The rapid generation of molecular in a relatively easy manner has made the cycloaddition reaction a powerful tool in the synthesis of different membered ring compounds. Clearly, iron catalysts are becoming a much more interesting and viable choice for this purpose. In this review, a number of promising results in the iron catalyzed cycloaddition reactions in the last decades were sum- marized. Special attention has been paid to the asymmetric cycloaddition reactions. cycloaddition, iron catalyst, asymmetric Citation: Wang C X, Wan B S. Recent advances in the iron-catalyzed cycloaddition reactions. Chin Sci Bull, 2012, 57: 23382351, doi: 10.1007/s11434-012-5141-z Cycloaddition reaction, which can construct several bonds in 2004, including addition, substitution, cycloaddition, re- simultaneously in a single step, is one of the most powerful duction and other reactions. At a later time, they also reviewed strategies for the synthesis of cyclic compounds from vari- the oxidative C–C coupling reactions [4] and the develop- ous unsaturated substrates such as alkynes, alkenes, allenes, ment of carbon-heteroatom and heteroatom-heteroatom bond nitriles, aldehydes, ketones, imines, etc.
    [Show full text]
  • Rhodium-Catalyzed Decomposition of Carbohydrate Diazo Esters By
    Rhodium-Catalyzed Decomposition of Carbohydrate Diazo Esters by Matthew LaLama Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in the Chemistry Program YOUNGSTOWN STATE UNIVERSITY August 2018 Rhodium-Catalyzed Decomposition of Carbohydrate Diazo Esters Matthew LaLama I hereby release this thesis to the public. I understand that this thesis will be made available from the OhioLINK ETD Center and the Maag Library Circulation Desk for public access. I also authorize the University or other individuals to make copies of this thesis as needed for scholarly research. Signature: Matthew J. LaLama, Student Date Approvals: Dr. Peter Norris, Thesis Advisor Date Dr. Douglas Genna, Committee Member Date Dr. John Jackson, Committee Member Date Dr. Salvatore A. Sanders, Dean of Graduate Studies Date iii ABSTRACT This thesis herein reports the synthesis of two diazo ester sugars and their decomposition in the presence of catalytic rhodium acetate dimer. Reactions were designed for the isolation of products formed through intramolecular C-H insertion reactions. However, no C-H insertion occurred, and instead this research led to the formation of a head-to-head- imine linked dimer not presently reported by previous lab members. iv Acknowledgements Firstly, I would like to thank Dr. Peter Norris, my advisor, for providing me with the opportunity to be a member of his research group. From providing me with my sophomore organic education, to his advice and tutelage while working as an undergraduate and graduate student in his lab, he has helped every step of the way. Thank you for all of your help, and thank you for playing a part in convincing me to become a chemistry major.
    [Show full text]