Total synthesis of somamide A, an Ahp (3-amino-6-hydroxy-2-piperidone)-containing cyclic depsipeptide

Abstract

The first total synthesis of somamide A ( 1 ), an Ahp (3-amino-6-hydroxy-2-piperidone)-containing cyclic depsipeptide, from the marine cyanobacterium Lyngbya majuscula is described. The efficient and stereospecific dehydration of the N-acyl threonine ester using Martin's sulfurane provided the ( Z)-2-amino-2-butenoic acid residue. The macrolactamization using FDPP(Ph 2P(O)OC 6F 5), the final installation of the Ahp moiety by oxidation with 1-hydroxy-1,2-benziodoxol-3(1 H)-one 1-oxide, and cyclization of the norvaline derivative to the cyclic hemiaminal afforded somamide A ( 1 ).