Abstract
Cyclodipeptide (diketopiperazine) consisting of α-amino acids with some polar side chains was synthesized by reaction of α-amino acid benzyl ester p-toluenesulfonate with N-carboxy α-amino acid anhydrides in acetonitrile. The reaction mechanism seems to be similar to the reaction of synthesis of diketopiperazine with alkyl side chains. Tyrosine was used as an ester component without protecting the hydroxyl group.
