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.
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