Stereoselectively synthesis and structural confirmation of dehydrodipeptides with dehydrobutyrine

Most of polypeptides containing alpha,beta-dehydroamino acids have important biological activity, so exploration of synthetic method has practical significance. In this paper, dipeptides were prepared from L-threonine by protecting of c-terminal allyl acetate, and condensing reaction with a series of N-Boc amino acid. Then, treatment of dipeptides obtained with DMAP, (Boc)(2)O and tetramethylguanidine in the acetonitrile occured beta-elimination reaction to yield stereoselectively dehydrodipeptides. Structures of dehydrodipeptides were confirmed by H-1 NMR, C-13 NMR and MS. Analysis of H-1 NMR, 2D NMR and crystal structure showed that the dehydrodipeptides were Z-configuration.