Amides, from acid derivatives polymers

FIGURE 3 Schematic representation of a pseudopoly (amino acid) derived from the side chain polymerization of a dipeptide carrying protecting groups X and Y. The wavy line symbolizes a nonamide bond. In this polymer, the amino acid side chains are an integral part of the polymer backbone while the termini have become pendant chains. In the backbone, amide and nonamide bonds strictly alternate. 

A further example of the utility of this approach involved the polymerization and manipulation of cholanic-acid-derived xanthate 59 (Scheme 14) [10]. Treatment of xanthate 59 with 15 equivalents of styrene provided polymer-bound steroid 60 in 85% yield. In this case a spacer unit was incorporated between the polymer and the substrate. The substrate was then modified at both the xanthate and carboxylic acid termini to provide N-cyclopropylamide 61. Cleavage from the polymer support was achieved using KOH in methanol and THF, and provided amide 62 in 62% yield. 

Chiral lithium amide bases have been used successfully in the asymmetric deprotonation of prochiral ketones [55, 56]. WUliard prepared polymer-supported chiral amines from amino acid derivatives and Merrifield resin [57]. The treatment of cis-2,6-dimethylcyclohexanone with the polymer-supported chiral lithium amide base, followed by the reaction with TMSCl, gave the chiral silyl enol ether. By using polymeric base 96, asymmetric deprotonation occurred smoothly in tetrahydrofuran to give the chiral sUyl enol ether (, S )-102 in 94% with 82% ee (Scheme 3.28). 

The compounds of the present study were prepared from the C-allyl sialic acid derivative described by Paulsen et al.102 and Vasella, et al.103 The ethyl ester of this compound was converted to the amide, shown. Completion of the synthesis involved reductive animation to the illustrated glucose based polymer thus giving the product. In one particular instance, the starting materials were combined to yield a product containing approximately 30% of the sialic acid analog. This polyvalent C-sialoside inhibited infection by influenza virus with an IC50 of 0.2 M. 

A. Borriello, L. Nicolais, S.J. Huang, Poly(amide-ester)s derived from dicarboxyUc acid and aminoalcohol, J. Appl. Polym. Sd. 95... 

Mallakpour S, Zarei M. Novel, thermally stable and chiral poly(amide-imide)s derived from a new diamine containing pyridine ring and various amino acid-based diacids fabrication and characterization. High Perform Polym 2013 25(3) 245-53. 

Carbonyl addition-elimination n. The single most important type of reaction mechanism which has been applied to the preparation of step-growth polymers is the addition-elimination reaction of the carbonyl double bond of carboxylic acids and carboxylic acid derivatives included in this general type of reaction are esterification amidation and anhydride formation from carboxylic acids, esters, amides, anhydrides and acid halides. 

Lozano M., Franco L., Rodriguez-Galan A., Puiggali J. Poly(ester amide)s derived from 1,4-butanediol, adipic acid and 1,6-aminohexanoic acid. Part ni substitution of adipic acid units by terephthahc acid units, Polym. Deg. Stab. 85 (2004) 595. 

Leznoff and Goldwasser (1977) used a hydroxymethylated polymer for monoblocking of symmetrical diacid chlorides. The unblocked acid chloride group was then converted to an amide and the polymer-bound derivatives were cleaved from the polymer and characterized as monoamide monoesters (Scheme 9-11). The functionalized products were obtained in high yield and in pure state, indicating that there was no observable double binding of the acids on polymer support. It was stressed that proper choice of the reaction conditions can alter the ability of the polymer to undergo interresin reactions. 

Preparation of the films from the solutions of the polymers in amides, or in sulphurous, or in phosphoric or other acid derivatives (e.g., dimethyl formamide, dimethyl acetamide, hexamethylphosphamide, etc.), or in chlorobenzene, m-cresol, formic acid, and so forth. 

The activation of acids by oxidation or dehydration of their derivatives has been studied by a German school. Oxidation of an acid diphenylhydrazide by JV-bromosuccinimide yields the azonium ion (96), which functions as a highly activated acid derivative, azobenzene being eliminated on nucleophilic attack. A related activation by oxidation has been performed in the solid phase by production of the polymer-bound azo-compound (97), nitrogen being expelled on amide-bond formation. Dehydrative activation is exemplified by conversion of the ester (98), prepared from the acid and 1,1-diphenylethylene glycol, into the enol ester (99). The generation of azo-compounds by anodic oxidation of hydrazides has been reported. All of these procedures have been utilized successfully in peptide synthesis. 

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