I. Efforts toward the total synthesis of (-)-crambidine. II. Reactions of Azy(3-Me)-containing peptides with thiols and selenols

An approach to (-)-crambidine, utilizing a key [4+2] annulation reaction between a thioimidate and an electron deficient vinyl carbodiimide, has been investigated. This approach has resulted in several advanced intermediates related to (-)-crambidine, but an efficient total synthesis of (-)-crambidine has not yet been completed. Additionally, an investigation into the base-promoted thiolysis and selenolysis of Azy(3-Me)-containing peptides has been performed. While thiols were found to have low reactivity with this class of electrophilic peptide residues, two S-linked glycopeptides were successfully synthesized. Benzeneselenol was found to be highly reactive with Azy(3-Me)-containing peptides, and a variety of synthetically useful selenopeptides have been generated.