Synthetic studies of cyclic peptides stephanotic acid methyl ester, celogentin C, and moroidin

An account of the total synthesis of stephanotic acid methyl ester and celogentin C is presented. The present synthesis features a tandem asymmetric Michael addition/bromination sequence for the synthesis of leucine-tryptophan moiety, and an oxidative coupling reaction to form the tryptophan-imidazole linkage. Moreover, the total synthesis of moroidin had also been studied, and three different synthetic strategies for the construction of the right-hand ring of moroidin were studied.