Amino acid esters

摘要

(A) (B) (I) + H2NR" R-CO-NH-R"+R-CO-NH-OH R = aryl R' = N-protected amino acid or peptide R' = aliphatic or amino acid derivs. The esters formed are optically active and may be used for the direct prepn. of the amide- or peptide bonding without isolation of the active hydroxamic esters and without loss of configuration. The new method gives active esters which retain their configuration. The catalysis B gives better yields and products with greater purity. The active esters are formed by reacting acid chlorides, opt. symmetrical anhydrides or acid activated with dicyclohexyldiimide, with hydroxamic acid or a salt. The esters are obtained by the reaction of hydroxamic acid chlorides with tert.