Highly Diastereoselective Peptide Chain Extensions of Unprotected Amino Acids with<i>N</i>-(Z-α-Aminoacyl)benzotriazoles

Abstract

Coupling an unprotected amino acid or dipeptide in partially aqueous solution with a readily available N-(Z-α-amino­acyl)benzotriazole or N-(Z-α-aminopetidoyl)benzotriazole affords N-terminal-protected di-, tri-, and tetrapeptides in yields of 85-98% (average 95% for 2a-i, 93% for 4a-f and 4a′, 86% for 5a-b) with minimal epimerization.