Amides synthesis, chemical

M. F. Lappert, P. P. Power, A. R. Sanger and R. C. Srivastava, Metal and Metalloid Amides Synthesis, Structures, and Physical and Chemical Properties Horwood-Wiley Chichester, 1980. 

Some groups have reported on their search for less reactive acylating agents, to suppress noncatalyzed chemical acylation and increase product enantiomeric excess. Irimescu and Kato carried out an enantioselective lipase catalyzed acylation of 1 phenylethylamine and 2 phenyl 1 propylamine by reacting the amines with carbox ylic acids in a nonsolvent system or in ionic liquids (Figure 14.9). The reaction equilibrium was shifted toward amide synthesis by the continuous removal of the... 

A. McKenna, Fatty Amides-Synthesis, Properties, Reactions, and Applications, Humko Chemical Division of Witco Corp., Memphis, Tenn., 1982. 

Although at high substrate concentrations (above about 50g l ) the reaction equilibrium of the enzymatic hydrolysis at pH 8 shifts noticeably away from complete hydrolysis, and at pH 5 lies towards amide synthesis, the reversal of the hydrolysis is not a usefiil method for resynthesizing the amide. The commercial value of 6-APA is about 75 per kilogram, and some of the new side chains are equally valuable. Unless the amide synthesis is achieved in high yield, calculated from both the carboxyl and the amino halves of the new penicillin, the process is unlikely to be viable. High yields of this kind have not been recorded for the reversal of the enzymatic process, and until they are, chemical processes will remain the standard methods for adding the new side chains. 

Amides are common structures and they are important and versatile synthons to prepare pharmaceuticals, agrochemicals, materials and some specialty chemicals. Many methods have been developed to synthesize primary amides, secondary amides as well as tertiary amides. The traditional process to construct amide bond is the acylation of amines with carboxylic acid or carboxylic acid daivatives such as acid chlorides as well as anhydrides [1, 2]. Furthermore, the Schmidt reaction [3] and Beckmann rearrangement [4] also have been well developed for the amide synthesis. Recently, some reviews have been well summarized the synthesis routes of these amides [5-17]. In this chapter, we will focus on the recent progresses about amide synthesis only by N, NH, or NH2 atoms incorporation nitrogenation strategy via C-H and/or C-C bond cleavage. A series of nitrogen sources such as sodium... 

Henriksen, D., Breddam, K., Moller, J., Buchardt, O. (1992). Peptide amidation by chemical protein engineering. A combination of enzymatic and photochemical synthesis. /. Am. Chem. Soc., 114,1876-1877. 

In 2007, Milstein reported an approach for the transition metal catalysed intermolecular formation of amides from alcohols and amines in the absence of a hydrogen acceptor (Scheme 12.19). In contrast with conventional amide synthesis from activated carboxylic acid derivatives which produces chemical waste, this environmentally benign approach produces hydrogen gas as the only byproduct. The catalyst used for this reaction is a dearomatised Ru(PNN)pincer complex which serves as a bifunctional catalyst. The ligands, as well as the metal centre, play a role in bond making or bond breaking steps of the catalytic cycle. 

See also PBT degradation structure and properties of, 44-46 synthesis of, 106, 191 Polycaprolactam (PCA), 530, 541 Poly(e-caprolactone) (CAPA, PCL), 28, 42, 86. See also PCL degradation OH-terminated, 98-99 Polycaprolactones, 213 Poly(carbo[dimethyl]silane)s, 450, 451 Polycarbonate glycols, 207 Polycarbonate-polysulfone block copolymer, 360 Polycarbonates, 213 chemical structure of, 5 Polycarbosilanes, 450-456 Poly(chlorocarbosilanes), 454 Polycondensations, 57, 100 Poly(l,4-cyclohexylenedimethylene terephthalate) (PCT), 25 Polydimethyl siloxanes, 4 Poly(dioxanone) (PDO), 27 Poly (4,4 -dipheny lpheny lpho sphine oxide) (PAPO), 347 Polydispersity, 57 Polydispersity index, 444 Poly(D-lactic acid) (PDLA), 41 Poly(DL-lactic acid) (PDLLA), 42 Polyester amides, 18 Polyester-based networks, 58-60 Polyester carbonates, 18 Polyester-ether block copolymers, 20 Polyester-ethers, 26... 

More recently, Williams has described the one pot synthesis of 2-substituted oxazoles 11 by the thermolysis of triazole amides 9 the reaction does not proceed photo-chemically.<92TL1033> Although the reaction does not involve addition to a nitrile, it is an interesting application of a diazo compound since the proposed zwitterionic intermediate 10 is a resonance form of a diazo imine, so formally the reaction may be thought of as a thermal decomposition of a diazo imine (Scheme 6). 

Primary phosphines (R-PHj) are an important ciass of compounds in organophosphorus chemistry. Aithough discovered over a century ago, their chemistry and appiications have gained prominence in recent years. This review discusses recent deveiopments on synthesis, moiecuiar structure, properties, and appiications of primary phosphines. In particular, discussions on synthesis and properties emphasize recent results from our laboratory on the chemical architecture of amide, thioether, and carboxylate functionalized primary bisphos-phines. The utility of bromo- and aminopropyl phosphines (X(CH2)3PH2 X=Br or NH2) as building blocks to produce designer primary phosphines that display exceptional oxidative stability is described. The review also discusses the utility of carboxylate functionalized primary phosphines for incorporation on to peptides and their potential applications in catalysis and biomedicine. 

The Medicinal Chemistry route introduced the oxadiazole fragment prior to installation of the 4-FBA (Scheme 6.1). The overall yield for these two steps was only 37%. The oxadiazole required a two-step synthesis and was a much more expensive reagent than 4-FBA. In order to improve the chemical yield, reduce cost and improve the overall process robustness, we investigated the amidation with 4-FBA prior to installing the oxadiazole moiety. 

Acryl amide is an important bulk chemical used in coagulators, soil conditioners and stock additives. The chemical synthesis has several drawbacks because the rate of acryl amide formation is lower than the formation of the by-product acrylic acid [54]. Further, the double bonds of the reactants and products cause by-product formations as well as formation of polymerization products. As a result of optimization with methods of molecular engineering, a very high activity of the biocatalyst nitrile hydratase at low temperature is yielded, enabling a successful biotransformation that is superior to the chemical route. Here, the synthesis is carried out at a low temperature of about 5°C, showing a conversion of 100%. 

Due to its wide application in peptide synthesis, 1-hydroxybenzotriazole 1001 is the most commonly used benzo-triazole derivative with hundreds of references in Chemical Abstracts each year. Utility of compound 1001 comes from its readiness to form esters with carboxylic acids in the presence of dehydrating agents (DAs). Obtained esters 1002 react eagerly with amines to produce amides 1003 in high yields (Scheme 165). More details about this application are given in Section 5.01.12. 

Applications of the cross-metathesis reaction in more diverse areas of organic chemistry are beginning to appear in the literature. For example, the use of alkene metathesis in solution-phase combinatorial synthesis was recently reported by Boger and co-workers [45]. They assembled a chemical library of 600 compounds 27 (including cisttrans isomers) in which the final reaction was the metathesis of a mixture of 24 oo-alkene carboxamides 26 (prepared from six ami-nodiacetamides, with differing amide groups, each functionalised with four to-alkene carboxylic acids) (Eq.27). 

---