DOCSLIB.ORG

Soda-Amine Pulping Reaction of Amines with Free Phenolic ß -O-4 Ethers

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Soda-Amine Pulping Reaction of Amines with Free Phenolic ß -O-4 Ethers Soda-amine pulping Reaction of amines with free phenolic ß -O-4 ethers ABSTRACT KEYWORDS The quinone methide from guaiacylglycol- ß-guaiacyl ether underwent Amines nucleophilic addition to the a-carbon with primary and secondary amines at Pulping 40°C. At pulping temperature, 170°C, only the primary amine adduct was Alkaline pulping detected. The quinone methide from guaiacylglycerol- ß-guaiacyl ether gave Quinones Formaldehyde analogous adducts at 40°C, but no quinone methide-amine adducts were Delignification detected at 170°C. Instead, the major products were the vinyl ether and a substituted vinyl ether which resulted from a Mannich reaction of the vinyl ether, amine, and liberated formaldehyde. John R. Obst Forest Products Laboratory, ForestService, U.S. Department of Agriculture, Madison,Wis. 53705 It has long been known that inclusion lowed to react with the quinone methide and can re-form the quinone methide in of certain amines in the soda pulping of generated from guaiacylglycol-ß-guaia­ soda liquor to ultimately yield the vinyl wood improves the selectivity of delig­ cyl ether, 1-(3-methoxy-4-hydroxy ether. The primary amine adducts are nification (1). More recently, the use of phenyl)-2-(2-methoxyphenoxy) ethanol more stable at high temperature than water-soluble primary amines has gen­ (I), and its diacetate. are those of the secondary amines. erated renewed interest in soda-amine Amines are known to undergo nucleo­ The reaction of amines with the vinyl pulping (2-4) and in the mechanism of philic addition to quinone methides (9). ether was unlikely, because the ether delignification. Wallis (5) has studied Reaction of the quinone methide (11) was formed in increasing amounts with the reaction of lignin-model compounds conveniently prepared from I diacetate time upon treatment of I with soda- with monoethanolamine (MEA), but the at 40°C (10) with primary and secon­ MEA (7). When the isolated vinyl ether significance of these reactions remains dary amines gave an adduct (III, Fig. 1) was treated with 33% n-propylamine to be demonstrated in alkaline-MEA in high yield (Table I). The vinyl ether and 0.5 N NaOH for 30 min at 170°C, no systems. Kubes et al. (6) considered a (IV) was the major product when a ter­ propylamine-quinone methide adduct delignification mechanism based on tiary amine was used. The n-propyla­ was detected. This lack of reversibility redox potentials of the spent pulping mine-quinone methide adduct was iso­ of the vinyl ether to re-form the quinone liquor but did not propose any chem­ lated and characterized by 1H and 13C methide is consistent with model stud­ ical mechanism. Obst and Sanyer (7) NMR, as well as by infrared and mass ies of kraft (11) and anthraquinone pulp­ have indicated that MEA may increase spectroscopy. Other primary and secon­ ing (12). delignification rate in a twofold man­ dary amine adducts were examined by The formation of a quinone methide­ ner: by reacting with quinone meth­ 1H NMR spectroscopy, and all spectra amine adduct (III) from I and primary ides, thereby preventing formation of were consistent with the general struc­ amines explains the low yields of guaia­ the vinyl ether with the beneficial effect ture III. col and vinyl ether previously reported of preventing lignin condensation re­ To more closely simulate wood pulp­ (7). Previous model studies showed simi­ actions; and by increasing the rate of ing conditions, model I was treated with lar reactions for both guaiacylglycol-ß­ cleavage of ß-ethers of etherified, or 0.33 N NaOH and various amines at ethers (I) and guaiacylglycerol-ß-ethers blocked, phenolic lignin moieties. This 170°C. A notable difference from the (V). Erythro-V triacetate gave a quinone paper presents the results of the reac­ results obtained at low temperature methide under mild conditions analo­ tions of free phenolic ß-O-4 ether lignin was that none, or only a trace, of the gous to that formed from I diacetate. models in soda-amine pulping liquors. secondary amine adduct was isolated This quinone methide also reacted with (Table II) and the yields of primary primary and secondary amines to give Resultsand discussion amine adducts were lower. When the an amine adduct (VI) (Table III, Fig. 2). n-propylamine-quinone methide ad- However, erythro-V treated with alka­ The reactions of quinone methides de­ duct (III, R = C3H7, R´ = H) prepared at li and amine at 170°C gave mainly IV rived from free phenolic ß-ethers in lig­ 40°C was treated with 0.5 N NaOH at and a C-5-substituted vinyl ether (VII) nin play a major role in determining 170°C for 30 min, only half of the adduct (Table III, Fig. 2) without any trace of delignification rates in soda, kraft, and was recovered. The diethylamine ad- quinone methide-amineadduct. The VII anthraquinone pulping (7). Also, the in­ duct (III, R = R´ = C2H5) treated under was formed by a Mannich reaction be­ creased delignification rate in soda-MEA the same conditions gave primarily the tween IV, formaldehyde liberated from pulping may in part be due to reaction vinyl ether and left only a trace of III. the terminal methylol group of the qui­ of the amine with quinone methides (7). Although amines are good nucleophiles, none methide, and amine. The VII was To test this proposal, amines were al­ they are also good leaving groups (9) also synthesized by treatment of either I Reprinted from Tappi, The Journal of the Technical Association of the Pulp and Paper Industry. Vol. 64, No. 10, October 1981, Copyright, 1981 by TAPPI, and reprinted by permission of the copyright owner. PULPING or IV with formaldehyde and amine in I. Products from the reaction of the quinone methide (II) soda liquor at 170°C. Both n-propyla­ from I diacetate with amines at 40°C mine-quinone methide adducts (III and Yield, % of theory VI, R = C3H7, R'= H) prepared from the acetates at 40°C gave only IV upon Recovered digestion with 0.5 N NaOH at 170°C. Amine Vinyl starting Guaiacol, resulting from ß-ether adduct ether material cleavage of V, also underwent a Man­ Amine (Ill) (IV) Guaiacol (I), % nich reaction with formaldehyde and amine. Although only one substituted Methylamine 86 0 Trace 0 guaiacol, 3-methoxy-4-hydroxybenzyl­ n-Propylamine 89 0 5.9 0 Dimethylamine 85 0 0.1 0 n-propylamine (VIII), was isolated in Diethylamine 84 0 . 3% yield, primary amines, guaiacol, and 4 Trimethylamine 0 60 0.4 27 formaldehyde may react to give other Triethylamine 0 71 . products (13). These condensation re­ 17 actions explain the low yields of IV and guaiacol reported previously (7). The difference in the reactions of I II. Products from the soda reaction of the quinone and V in soda-amine liquor at 170°C methide from I with amines at 170°C may be that the rate of formation of Yield, % of theory vinyl ether from the quinone methide of V is much higher than the rate of Amine Vinyl amine nucleophilic addition. It has been adduct ether shown (14) that vinyl ether formation Amine (III) (IV) Guaiacol from V is faster than from I, as loss of Methylamine 72 5 10 formaldehyde is more facile than pro­ n-Propylamine 63 11 6 ton removal from the corresponding Dimethylamine 5 63 17 quinone methides. The formation of Diethylamine 0 62 20 vinyl ether from the amine adduct VI Trimethylamine 0 74 14 most likely proceeds through the qui­ Triethylamine 0 69 11 none methide of V since digestion of the methyl ether of VI (R = C3H7, R' = H) with 0.5 N NaOH at 170°C did not yield treating both I and V with soda-amine creased quinone methide formation in the methyl ether of IV. liquor relative to the yields upon treat- the presence of amines. Solvent effects The lower yields of guaiacol upon ing with soda may be a result of in- have been shown (15) to have a major 1. Soda-amine (R = CH3, C2H5, C3H7; R' = C2H5, C2H5) reactions of guaiacylglycol-ß -guaiacyl ether (I). 100 Vol. 64, No. 10 October 1981 / Tappi III. Products from the soda amine reactions of effect on product distribution on treat- V triacetate at 40° C and V at 170° C ment of I with base. Tertiary amines Yield, % of theory have been used as solvents to promote quinone methide formation (9). Amine Vinyl Substituted adduct ether vinyl ether Amine (VI) (IV) (VII) Guaiacol Summary and conclusions V triacetate at 40° C Guaiacylglycol- ß-guaiacyl ether (I) di­ gested in alkali with primary amines Methylamine 81 0 0 0 at 170°C gave III via nucleophilic ad­ n-Propylamine 79 0 0 0 dition to the quinone methide. The qui­ Dimethylamine 82 0 0 0 none methide from I diacetate prepared Diethylamine 79 0 0 0 at 40°C underwent nucleophilic addi­ tion in high yield with both primary Vat 170°C and secondary amines. The quinone Methylamine 0 51 26 3.9 methide from guaiacylglycerol-ß-guai­ n -Propylamine 0 54 22 4.1 acyl ether (V) triacetate at 40°C reacted Dimethylamine 0 24 56 3.9 analogously to that from I diacetate. In Diethylamine 0 52 26 2.6 contrast, when V was digested in soda­ amine liquor at 170°C, no quinone 2. Soda-amine (R = CH3, C2H5, C3H7; R' = CH3, C2H5) reactions of guaiacylglycerol-ß -guaiacyl ether (V) Tappi / October 1981 Vol. 64, No. 10 101 PULPING methide addition product was detected. NMR data of the acetylated adduct (VII) prepared with methylamine and Instead the major products were IV showed these major differences: δ 3.12 n-propylamine coincidentally gave cis- and a C-5-substituted vinyl ether (VII), (t, C-1 propyl methylene, J = 7 Hz); Hα at the same chemical shift as for IV.
Load more

Recommended publications
  • Abstract Multicomponent Reactions of Salicylaldehyde, Cyclic Ketones, and Arylamines Through Cooperative Enamine-Metal Lewis
    ABSTRACT MULTICOMPONENT REACTIONS OF SALICYLALDEHYDE, CYCLIC KETONES, AND ARYLAMINES THROUGH COOPERATIVE ENAMINE-METAL LEWIS ACID CATALYSIS by Ryan Gregory Sarkisian Multicomponent reactions (MCRs) are the most atom economic, highly selective, and convergent type of reaction. This allows for a reaction to have a wide scope and allows for maximization of the complexity of a product. Catalyzing these MCRs with asymmetric catalysis is a novel way to introduce stereocontrol into highly complex molecules with various functional groups. Asymmetric catalysis is considered the most efficient method for constructing highly functionalized optically active stereopure compounds. There are three pillars of asymmetric catalysis: biocatalysis, transition metal catalysis, and organocatalysis. This research focuses on two of these pillars, transition metal catalysis and organocatalysis, working cooperatively to catalyze this MCR. The focus is to educate or refresh the audience on the basic topics that make up the complexity of the MCRs being catalyzed by cooperative asymmetric catalysis. Ultimately to explore the cooperative catalysts used to synthesize both the racemic and asymmetric three fused ring products (9-((4-methoxyphenyl)amino)-2,3,4,4a,9,9a-hexahydro-1H-xanthen-4a-ol). MULTICOMPONENT REACTIONS OF SALICYLALDEHYDE, CYCLIC KETONES, AND ARYLAMINES THROUGH COOPERATIVE ENAMINE-METAL LEWIS ACID CATALYSIS A THESIS Submitted to the Faculty of Miami University in partial fulfillment of the requirements for the degree of Master of Science Department of
    [Show full text]
  • Catalytic Direct Asymmetric Michael Reactions
    ORGANIC LETTERS 2001 Catalytic Direct Asymmetric Michael Vol. 3, No. 23 Reactions: Taming Naked Aldehyde 3737-3740 Donors Juan M. Betancort and Carlos F. Barbas III* The Skaggs Institute for Chemical Biology and the Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037 [email protected] Received September 5, 2001 ABSTRACT Direct catalytic enantio- and diastereoselective Michael addition reactions of unmodified aldehydes to nitro olefins using (S)-2-(morpholinomethyl)- pyrrolidine as a catalyst are described. The reactions proceed in good yield (up to 96%) in a highly syn-selective manner (up to 98:2) with enantioselectivities approaching 80%. The resulting γ-formyl nitro compounds are readily converted to chiral, nonracemic 3,4-disubstituted pyrrolidines. The Michael reaction is generally regarded as one of the Typically, carbon nucleophiles that contain an active most efficient carbon-carbon bond forming reactions, and methylene center such as malonic acid esters, â-keto esters, studies concerning this reaction have played an important nitroalkanes, etc. have been studied in the Michael reaction. role in the development of modern synthetic organic Carbonyl compounds, and ketones in particular, have gener- chemistry.1 As the demand for optically active compounds ally only been used as donors following their preactivation has soared in recent years, much progress has been made in by conversion into a more reactive species such as enol or the development of asymmetric variants of this reaction, enamine equivalents.5,6 In these cases, additional synthetic providing for the preparation of Michael adducts with high enantiomeric purity.2 Though remarkable advances have been (3) (a) Chataigner, I.; Gennari, C.; Ongeri, S.; Piarulli, U.; Ceccarelli, S.
    [Show full text]
  • Copyrighted Material
    Index Abbreviations receptor sites 202, 211 weak 122 amino acids, Table 500–1 muscarinic 413 weak, pH calculation 147–8 nucleic acids 551 nicotinic 413 Acid–base nucleotides, Table 551 as quaternary ammonium salt 202 catalysis, enzymes 516 peptides and proteins 504 Acetylcholinesterase equilibria 121 phosphates and diphosphates 277 enzyme mechanism 519–21 interactions, predicting 155–7 structural, Table 14 hydrolysis of acetylcholine 279 Acidic reagents, Table 157 ACE (angiotensin-converting enzyme) inhibitors 279 Acidity enzyme action 532 Acetyl-CoA carboxylase, in fatty acid acidity constant 122 inhibitors 532 biosynthesis 595 bond energy effects 125 Acetal Acetyl-CoA (acetyl coenzyme A) definition 121 in etoposide 233 as acylating agent 262 electronegativity effects 125 formation 229 carboxylation to malonyl-CoA 595, hybridization effects 128 polysaccharides as polyacetals 232 609 inductive effects 125–7 as protecting group 230 Claisen reaction 381 influence of electronic and structural Acetal and ketal enolate anions 373 features 125–34 cyclic, as protecting groups 481 in Krebs cycle 585 and leaving groups, Table 189 groups in sucrose 231 from β-oxidation of fatty acids 388 pKa values 122–5 Acetaldehyde, basicity 139 as thioester 262, 373 resonance / delocalization effects 129–34 Acetamide, basicity 139 Acetylene, bonding molecular orbitals 31 Acidity (compounds) Acetaminophen, see paracetamol Acetylenes, acidity 128 acetone 130 Acetoacetyl-CoA, biosynthesis from N-Acetylgalactosamine, in blood group acetonitrile 365 acetyl-CoA 392
    [Show full text]
  • Comparative Total Syntheses of Strychnine
    Comparative Total Syntheses of Strychnine N C D MacMillan Group Meeting N H O H A H B E Nathan Jui H N N H H F G July 22, 2009 O O O References: Pre-Volhardt: Bonjoch Chem. Rev. 2000, 3455. Woodward Tetrahedron, 1963, 247. Volhardt J. Am. Chem. Soc. 2001, 9324. Magnus J. Am. Chem. Soc. 1993, 8116. Martin J. Am. Chem. Soc. 2001, 8003. Overman J. Am. Chem. Soc. 1995, 5776. Bodwell Angew. Chem. Int. Ed. 2002, 3261. Kuehne J. Org. Chem. 1993, 7490. Mori J. Am. Chem. Soc. 2003, 9801. Kuehne J. Org. Chem. 1998, 9427. Shibasaki Tetrahedron 2004, 9569. Rawal J. Org. Chem. 1994, 2685. Fukuyama J. Am. Chem. Soc. 2004, 10246. Bosch, Bonjoch Chem. Eur. J. 2000, 655. Padwa Org. Lett. 2007, 279. History and Structure of (!)-Strychnine ! Isolated in pure form in 1818 (Pelletier and Caventou) ! Structural Determination in 1947 (Robinson and Leuchs) ! 24 skeletal atoms (C21H22N2O2) ! Isolated in pure form in 1818 (Pelletier and Caventou) N ! Over !25 07 -pruinbglisc,a 6ti-osntesr epoecrteaninteinrgs to structure ! Structural Determination in 1947 (Robinson and Leuchs) ! Notor!io u Ss ptoirxoicne (nletethr a(lC d-o7s) e ~10-50 mg / adult) N H H ! Over 250 publications pertaining to structure O O ! Comm!o nClyD uEs eridn gr osdyesntet mpoison ! Notorious poison (lethal dose ~10-50 mg / adult) ! Hydroxyethylidine Strychnos nux vomica ! $20.20 / 10 g (Aldrich), ~1.5 wt% (seeds), ~1% (blossoms) "For it's molecular size it is the most complex substance known." -Robert Robinson History and Structure of (!)-Strychnine ! 24 skeletal atoms (C21H22N2O2) N ! 7-rings, 6-stereocenters ! Spirocenter (C-7) N H H O O ! CDE ring system ! Hydroxyethylidine "For it's molecular size it is the most complex substance known." -Robert Robinson "If we can't make strychnine, we'll take strychnine" -R.
    [Show full text]
  • Chem 345 Pset 22 Key 1.) for Aldol, Michael, Claisen, and Mannich
    Chem 345 PSet 22 Key 1.) For Aldol, Michael, Claisen, and Mannich reactions, the first step is the creation of a nucleophile. Under basic conditions, the nucleophile is an enolate. Under acidic conditions, the nucleophile is an enol. Draw the mechanism for the formation of both species and then draw the reaction backwards. O NaOH O H H O HCl OH H H 2.) In the case of a Mannich reaction, the electrophile (an imine) must also be made. Draw the mechanism for the forward and backward reaction: O MeNH2 N H H cat. AcOH H H 3.) When a secondary amine is used and the carbonyl has an enolizable proton, an enamine can be formed. Are enamines nucleophilic or electrophilic? Nucleophilic H O N N H2O H cat. AcOH H enamine N N H H enamine 4.) The following reaction is the Lobry-de-Bruyn-von-Ekenstein reaction. Don’t worry about the name. I only recently found out that that was the official name for the rearrangement leading from glucose to fructose or mannose and back again. I was taught it under a different name: the Carbohydrate Game. Under acidic or basic conditions, it is possible that the following sugars (glucose, fructose, and mannose) are in equilibrium with each other. Draw the acid catalyzed version and the base catalyzed version. (Hint: this is just a repeat of question 1.) O O H H H2C OH + + HO H H3O H OH H3O O or or HO- HO- HO H HO H HO H H OH H OH H OH H OH H OH H OH H2C OH H2C OH H2C OH D-glucose D-fructose D-mannose O O H H H2C OH + + HO H H3O H OH H3O O or or HO- HO- HO H HO H HO H H OH H OH H OH H OH H OH H OH H2C OH H2C OH H2C OH D-glucose D-fructose D-mannose The sugars are drawn in a Fisher projection (or what I think of is a dead cat projection).
    [Show full text]
  • Heterocyclic Chemistrychemistry
    HeterocyclicHeterocyclic ChemistryChemistry Professor J. Stephen Clark Room C4-04 Email: [email protected] 2011 –2012 1 http://www.chem.gla.ac.uk/staff/stephenc/UndergraduateTeaching.html Recommended Reading • Heterocyclic Chemistry – J. A. Joule, K. Mills and G. F. Smith • Heterocyclic Chemistry (Oxford Primer Series) – T. Gilchrist • Aromatic Heterocyclic Chemistry – D. T. Davies 2 Course Summary Introduction • Definition of terms and classification of heterocycles • Functional group chemistry: imines, enamines, acetals, enols, and sulfur-containing groups Intermediates used for the construction of aromatic heterocycles • Synthesis of aromatic heterocycles • Carbon–heteroatom bond formation and choice of oxidation state • Examples of commonly used strategies for heterocycle synthesis Pyridines • General properties, electronic structure • Synthesis of pyridines • Electrophilic substitution of pyridines • Nucleophilic substitution of pyridines • Metallation of pyridines Pyridine derivatives • Structure and reactivity of oxy-pyridines, alkyl pyridines, pyridinium salts, and pyridine N-oxides Quinolines and isoquinolines • General properties and reactivity compared to pyridine • Electrophilic and nucleophilic substitution quinolines and isoquinolines 3 • General methods used for the synthesis of quinolines and isoquinolines Course Summary (cont) Five-membered aromatic heterocycles • General properties, structure and reactivity of pyrroles, furans and thiophenes • Methods and strategies for the synthesis of five-membered heteroaromatics
    [Show full text]
  • Mannich Reaction
    1. Introduction 1.1- Mannich Reaction The Mannich reaction is three component condensation in which a compound containing an active hydrogen atom is allowed to react with formaldehyde and an NH-amine derivative . Secondary amines rather than primary amines and ammonia are employed , the resulting product (Mannich Base ) is an amine compound having the N atom linked to the R substrate through a methylene group 1,2. The aminoalkylation of CH-acidic compounds was described by several authors as early as the 19th. century. However, it was Carl Mannich who was the first to recognize the enormous significance of this reaction , and it was he who extended the chemistry into a broad based synthetic methodology through systematic research. Since then this reaction that now carries his name has developed into one of the most important C-C bond-forming reactions in organic chemistry3,4. The Mannich reaction is a classical method for the preparation of β -aminoketones and aldehydes (Mannich bases) and, as such, is one of the most important basic reaction types in organic chemistry. It is the key step in the synthesis of numerous pharmaceuticals and natural products3,4. 1 The Mannich reaction can be presented by the following equation: The essential feature of the reaction is the replacement of the active hydrogen atom by an aminomethyl or substituted aminomethyl group. The symbolizes the active hydrogen component which includes ketones, aldehydes, acids, esters, phenols, acetylenes, picolines, nitroalkanes and quinolines1,2. 1.2- Mechanism of the Mannich reaction The mechanism of the Mannich reaction has been well investigated, the condensation reaction occurs in two steps: first, the amine reacts with formaldehyde to give condensation product (5 ), (6), ( 7) (step I) which then attacks the substrate R-H (step II) .The reaction does not normally follow the other possible route (step III and IV) ; however, some successful reaction between hydroxymethyl derivatives (8) and alkylamines to give Mannich bases (9) should be mentioned .
    [Show full text]
  • Enantioselective Total Synthesis of (-)-Strychnine1 Scheme1
    J. Am. Chem. SOC.1993,115, 9293-9294 9293 Enantioselective Total Synthesis of (-)-Strychnine1 Scheme1 Steven D. Knight, Larry E. Overman,' and Garry Pairaudeau Department of Chemistry University of California Imine, California 9271 7-2025 Received July 8, 1993 OTlPS Strychnine (1) has played a vital role in the development of d h,i natural productschemistry. First isolated in 1818 fromstrychnos ignatii by Pelletier and Caventou, strychnine was among the first plant alkaloids obtained in pure form. After decades of inves- OBU' (-)-Strychnine(1) tigation, the structural elucidation of strychnine in 1946 repre- sented one of the crowning accomplishments of classical structural chemistry.394 Its total synthesis by Woodward only 8 years later was an achievement of even greater significance, since prior to this feat no compound approaching the complexity of strychnine ,oms had been prepared by chemical synthesis.* That strychnine's P' seven rings displayed on only 24 skeletal atoms still represents a formidable challenge for total synthesis is apparent in the fact that only last year was a second total synthesis of strychnine published by Magnus and co-workers.6 This synthesis, like the pioneering Woodward synthesis, involved intersection with an intermediate available by degradation of stry~hnine.~.~Most recently, two syntheses of (*)-strychnine have been communicated by the groups of Stork' and Kuehne.* Herein we report the first asymmetric total synthesis of (-)-strychnine. This highly efficient total synthesis features the use of the cationic aza-Cope-Mannich reaction to assemble the pentacyclic strychnan c~re.~J~ The preparation in enantiopure form of the unsaturated azabicyclo[3.2.
    [Show full text]
  • Asymmetric Catalysis in Aqueous Media*
    Pure Appl. Chem., Vol. 79, No. 2, pp. 235–245, 2007. doi:10.1351/pac200779020235 © 2007 IUPAC Asymmetric catalysis in aqueous media* Shu– Kobayashi Graduate School of Pharmaceutical Sciences, The University of Tokyo, The HFRE Division, ERATO, Japan Science and Technology Agency (JST), Hongo, Bunkyo-ku, Tokyo 113-0033, Japan Abstract: Lewis acid catalysis has attracted much attention in organic synthesis because of unique reactivity and selectivity attained under mild conditions. Although various kinds of Lewis acids have been developed and applied in industry, these Lewis acids must be gener- ally used under strictly anhydrous conditions. The presence of even a small amount of water handles the reactions owing to preferential reactions of the Lewis acids with water rather than the substrates. In contrast, rare earth and other metal complexes have been found to be water- compatible. Several catalytic asymmetric reactions in aqueous media, including hydroxy- methylation of silicon enolates with an aqueous solution of formaldehyde in the presence of Sc(OTf)3–chiral bipyridine ligand or Bi(OTf)3–chiral bipyridine ligand, Sc- or Bi-catalyzed asymmetric meso-epoxide ring-opening reactions with amines, and asymmetric Mannich- type reactions of silicon enolates with N-acylhydrazones in the presence of a chiral Zn cata- lyst have been developed. Water plays key roles in these asymmetric reactions. Keywords: reactions in aqueous media; Lewis acids; catalytic asymmetric reactions; hydroxymethylation of silicon enolates; Sc(OTf)3–chiral bipyridine ligand. INTRODUCTION Organic reactions in aqueous media are of current interest owing to the key role played by water as a solvent for green chemistry [1].
    [Show full text]
  • Asymmetric Synthesis of C–F Quaternary Α-Fluoro-Β-Amino-Indolin
    RSC Advances View Article Online PAPER View Journal | View Issue Asymmetric synthesis of C–F quaternary a-fluoro- b-amino-indolin-2-ones via Mannich addition Cite this: RSC Adv.,2017,7,5679 reactions; facets of reactivity, structural generality and stereochemical outcome† Chen Xie,a Wanxing Sha,a Yi Zhu,a Jianlin Han,*a Vadim A. Soloshonokbc and Yi Pana Reported herein is a new approach for the preparation of enantiomerically pure a-fluoro-b-amino-indolin- Received 3rd December 2016 2-ones possessing tetrasubstituted fluorinated stereogenic centers. This method includes the Accepted 27th December 2016 detrifluoroacetylative in situ generation of tertiary enolates followed by Mannich reaction with (Ss)- DOI: 10.1039/c6ra27710a sulfinylimines. The operationally convenient conditions coupled with perfect diastereoselectivity and www.rsc.org/advances functional substituent compatibility bode well for widespread application of this new synthetic method. Creative Commons Attribution 3.0 Unported Licence. Fluoro-organic chemistry plays an essential role in furthering solutions. Over the last several years, our group has contributed numerous technological advancements, most notably in the to this research area by the development of cyclic enolates 2 energy,1 food2 and healthcare industries.3 Consequently, the (eqn (2)) allowing preparation of structurally complex products current interest in the synthesis of uorine-containing possessing tetrasubstituted uorinated stereogenic centers.13 compounds is at an all-time high, addressing the emerging The
    [Show full text]
  • The Robinson-Mannich Base Synthesis Applied to Substituted
    THE ROBINSON- MANNICH BASE SYNTHESIS APPLIED TO SUBSTITUTED OETOACETIC ESTERS by RICHARD FRANCIS LAPOBli: A THESIS subln1tted to OREGON 6TA7!E COI..t..iX}li: in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY June 1954 IXllffiDT Redacted for Privacy t & errur of h;lar Redacted for Privacy 6r1*m of Bq:stmt Redacted for Privacy chrtflra sqr fiel Sreffir ffit*­ Redacted for Privacy IH rf ffi&rr*r l**rrfi Lt tlrmlr lr firr $rpri ry lu.jltr Frlrtrt'rlrrr TABLE OF CONTENTS Page Introduction. • • . • .. • • • •· • • .. 1 B1stor1caJ.. • • • • • • • • • • • 4 Discussion of Results .. .• • .. • • • • • • • • • • 9 Experimental. • • • • • • • ·• • .. 32 Summary • • • . .. .. ,,.. • .. • • • • • . • • • • 42 Bibliography. • .. .. • .. .. • • • • • • • • • " LISf OF FIGURES Figure 1. • • • • • • ., • • . 3 Figure 2. • • • .. .. • • .. .. • • • • .. • • • .. • 6 F1:gure ... 3. •· " • • • • • • • 29 Figure 4. • • • • ·• .. • . ·• • • • • • • 30 F1gure 5. • • • • ,. • • • '1 ACKNOWLEDGMENT The author \'T1sbes to express his thanks to the E. I . duPont de Nemours and OompallJ (Inc. ) for assistance during the 1952-1953 y-ear in the form of a pre-doctoral fellowship. Gx-atef'ul thanks are also e;xtended to DP. Albert V.. Logan :for his guidance and help while this ~1ork was 1n progress and to his colleague, Dr. E. N. Marvell. :for his helpful suggestions. This work was supported. 1n part b7 the U. s. Atomic Energy Commission under contract with Oregon State College. Ded1cated to my wire. Genie THE ROBINSON- NICH BASE SYNTHESIS APPLIED TO SUBSTITUTED ACETOACETIC ESTERS INTRODUCTION The purpose of this investigation was to determine the feasibility of synthesizing certain substituted naphthalenes containing a cl4 atom placed in a known posi­ t ion in one of the rings. A contemplated study of the mode, of reaction of the Jacobsen rearrangement made it desirable to know whether or not these compounds m1g}lt be made conveniently, 1n a high state of purity and in good yield.
    [Show full text]
  • One-Pot Enol Silane Formation-Mukaiyama–Mannich
    CORE Metadata, citation and similar papers at core.ac.uk Provided by University of Richmond University of Richmond UR Scholarship Repository Chemistry Faculty Publications Chemistry 9-2013 One-Pot Enol Silane Formation- Mukaiyama–Mannich Addition of Ketones, Amides, and Thioesters to Nitrones in the Presence of Trialkylsilyl Trifluoromethanesulfonates C. Wade Downey University of Richmond, [email protected] Carolyn M. Dombrowski Erin N. Maxwell Chelsea L. Safran Odamea A. Akomah Follow this and additional works at: http://scholarship.richmond.edu/chemistry-faculty- publications Part of the Organic Chemistry Commons This is a pre-publication author manuscript of the final, published article. Recommended Citation Downey, C. Wade; Dombrowski, Carolyn M.; Maxwell, Erin N.; Safran, Chelsea L.; and Akomah, Odamea A., "One-Pot Enol Silane Formation-Mukaiyama–Mannich Addition of Ketones, Amides, and Thioesters to Nitrones in the Presence of Trialkylsilyl Trifluoromethanesulfonates" (2013). Chemistry Faculty Publications. 10. http://scholarship.richmond.edu/chemistry-faculty-publications/10 This Post-print Article is brought to you for free and open access by the Chemistry at UR Scholarship Repository. It has been accepted for inclusion in Chemistry Faculty Publications by an authorized administrator of UR Scholarship Repository. For more information, please contact [email protected]. FULL PAPER DOI: 10.1002/ejoc.200 ((will be filled in by the editorial staff)) One-Pot Enol Silane Formation-Mukaiyama–Mannich Addition of Ketones, Amides, and Thioesters to Nitrones in the Presence of Trialkylsilyl Trifluoromethanesulfonates C. Wade Downey,* [a] Carolyn M. Dombrowski, [a] Erin N. Maxwell, [a] Chelsea L. Safran, [a] and Odamea A. Akomah [a] Keywords: Nitrones / Mukaiyama addition / Mannich addition / Silyl triflates / hydroxylamines Ketones, amides, and thioesters form enol silanes and add to N- ((Abstract Text----Continued)) phenylnitrones in one pot in the presence of trimethylsilyl trifluoromethanesulfonate and trialkylamine.
    [Show full text]