The first total syntheses of JBIR-06 and two analogous depsipeptides, 12-membered antimycin-class antibiotics, have been accomplished via Shiina macrolactonization. Comparison of the spectroscopic data of the synthesized compounds with those reported for natural products verified that the absolute configutation of the natural products was (2S, 4S, 6S, 7R, 14S).

First total syntheses of JBIR-04 and unantimycin A have been achieved. Comparison of our spectroscopic data with those reported for natural samples verified the structure of the natural products; (2S,4S,6S,7R,9S,28S) configuration was thus assigned via total synthesis.