SCHEDULED MAINTENANCE
Polypeptides. Part XIII. Preparation of α-aza-amino-acid (carbazic acid) derivatives and intermediates for the preparation of α-aza-peptides
Abstract
Esters and amides of several α-aza-amino-acids (carbazic acids), and intermediates of use in the introduction into peptides of α-aza-glycyl, -alanyl, -valyl, -leucyl, -isoleucyl, -phenylalanyl, -tyrosyl, -tryptophyl, -prolyl, -aspartyl, -asparaginyl, -glutamyl, -glutaminyl, and -pyroglutaminyl residues are described. t-Butyl 3-alkyl- or -aralkyl carbazates, obtained by catalytic hydrogenation of the corresponding hydrazones, were the most versatile intermediates; they were converted in high yield into α-aza-amino-acid esters and amides, gave α-aza-dipeptide esters when treated with α-isocyanato-esters, and afforded ‘active esters’ of N-t-butoxycarbonyl-α-aza-amino-acids when treated with 2,4,5-trichlorophenyl chloroformate.
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