Carbobenzoxyamino acids

H Schiissler, H Zahn. Contribution on the course of reaction of carbobenzoxyamino acids with dicyclohexylcarbodimide. Chem Ber 95, 1076, 1962. 

H Medzihradsky-Schweiger. Promoted hydrogenolysis of carbobenzoxyamino acids in the presence of organic bases. Acta Chim (Budapest) 76, 437, 1973. 

Coupling of N-carbobenzoxyamino acids with diphenyl 1-aminoalkanephosphonates by the DCC method resulted in the formation of mixtures of diastereoisomers enriched in one of diastereoisomers,i.e. they appeare to form in nonequimolar quantities.lt is probably due to kinetic control of the reaction.On the other hand the MCA method gave an equimolar mixtures of diastereoisomers. 

The chloride (1) reacts with an N-carbobenzoxyamino acid in methylene chloride at 0° to form an activated anhydride (2) which can be condensed with a free amino acid to give a dipeptide (3) and saccharin, which can be separated because of its greater acidity. ... 

Prepared in quantitative yield by refluxing p-nitrophenol with trifluoroacetic anhydride, the reagent reacts rapidly with a carbobenzoxyamino acid at room Icmperature to give the p-nitrophenyl ester. The reaction with a carbobenzoxy peptide is slower and requires heat or a long reaction period. p-Nitrophenyl trichloro-ncetate is active only in refluxing pyridine and gives p-nitrophenyl esters in poor yield. 

Efforts have been made to design artificial enzymes with enantioselectivity by introducing chiral microenvironments on polymers. For example, PEI derivatives containing L-histidine moieties were prepared, and up to 3.6-fold rate difference was observed for the hydrolysis of D- and L-)V-carbobenzoxyamino acid p-nitrophenyl esters. ... 

Peptide synthesis. Zervas and co-workers prepared phenacyl esters of amino acids by treating a carbobenzoxyamino acid with phenacyl bromide and triethylamine... 

DeTar et at.2 give a detailed procedure for the preparation of several p-nitro-phenyl esters of carbobenzoxyamino acids. 

N-Acylamino acids, carbobenzoxyamino acids, proteins, and other compounds quite readily split by acid, are conveniently esterified with cold dil. anhydrous methanolie HC1. (E. s. R. L. M. Synge, Biochem. J. 42, 99 (1948) s. a. H. Fracnkel-Conrat- and H. S. Olcott, J. Biol. Chem. 161, 259 (1945).)... 

Carbenicillin isocyanate, 533-535 Carbobenzoxyalanylglycylphenylalanyl-chloromethyl ketone, 206 Carbobenzoxyamino acid imidazolide, reduction of, 222... 

Benzyl N-(p-chIorophenylthio)carbamate allowed to react 10 min. at -20 with K-tert-butoxide in dimethylformamide then 10 hrs. with p-nitrobenzyl bromide benzyl N-p-nitrobenzyl-N-(p-chlorophenylthio)carbamate (Y 87%) treated 15 min. with p-chlorobenzenethiol in dimethylformamide -> benzyl N-p-nitro-benzylcarbamate (Y ca. 100%). F. e., also N-carbobenzoxyamino acids, s. T. Ta-guchi and T. Mukaiyama, Chem. Lett. 1973, 1. 

Attempts to prepare the compound l,4-(Bu3Sn 0)2C(F from tetralluoro-hydroquinone and tri-n-butyltin chloride have yielded only tri>n butyltin fluoride, whereas the phenate CfFs O-SnBuj is readily obtained from the chloride and pentafluorophenol. The conversion of pentafiuorophenol into JV-carbobenzoxyamino-acid and peptide pentafluorophenyl esters useful as intermediates in peptide synthesis has been described. ... 

Peptides. Benzenesulfonyl chloride added at -10° to a soln. of L-2-(carbo-benzoxyamino) butyric acid in pyridine, after 10 min. glycine p-nitrobenzyl ester p-toluenesulfonate added, stirring continued 30 min. at -10° and 2 hrs. without cooling p-nitrobenzyl N- [l-2- (carbobenzoxyamino) butyryl] -glycinate. 

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