Stereochemistry of iejimalide B

The absolute configurations at five chiral centers, except for C-32(S) reported previously, in iejimalide B (1), a potent cytotoxic 24-membered macrolide isolated from a tunicate Eudistoma cf. rigida, were assigned as 4R, 9S, 17S, 22S, and 23S on the basis of detailed analysis of NMR data and chemical means. Furthermore, the structure of iejimalide B was revised from 2 (original: 13E) to its 13Z-isomer (1).