Synthesis and biological analysis of truncated calyculone H.

Herein, we report for the first time the design and linear synthesis of a truncated calyculone H () that lacks the telltale isopropyl/isopropylene groups, whereas the 12-membered macrocycle remains intact. Key steps for the framework of target molecule include allylic oxidation using SeO, Sharpless asymmetric epoxidation, Barbier zinc allylation, and ring-closing metathesis (RCM) reactions. A second truncated "calyculone-like" analogue, , with a different oxidation pattern around the ring was also synthesized following a similar strategy. Screening for in vitro cytotoxicity against a panel of 60 human cancer cell lines revealed that was as potent if not more so (for a few cell lines) than the natural product calyculone A ().