The synthesis of a marine cytotoxic cyclic depsipeptide obyanamide has been accomplished. The key steps include assembling liner pentapeptide via Yamaguchi esterification and HATU-promoted ring closing. The structure of the synthetic sample was identified by ^1H and ^13C NMR, H-H COSY, HMQC, HMBC, and HRESIMS, but appears to be different from that of the marine natural product.
The protected （2S,4R）-2-amino-4-methyldecanoic acid, a proposed component of culicinins has been synthesized over 10 steps and in total 28% yields using Wittig reaction and Schollkopf amino acid synthesis as key steps.
Wei Zhang Tian Tian Sun Duo Mei Jun Fei Wang Ying Xia Li
