Marine Terpenes and Terpenoids. V

Sarcophytol A (1a), a potent anti-tumor-promotor cembranoid from the soft coral Sarcophyton glaucum, was subjected to various oxidation reactions. m-Chloroperbenzoic acid oxidation of 1a gave two epoxides (2a, 2b) which were converted to the corresponding diols 6b, 11b, 12b, 12'b and triols 4b, 9b. Lithium aluminum deuteride reduction of 2a gave a C-7 monodeuterated diol; this was used as a model experiment for the tritiation of 1a. Chromic acid oxidation of 1a gave seco-cembranoids 13b-18, a dienone 19, and a dihydrofuran derivative 20a. Sarcophytol A acetate (1b) was less reactive in chromic acid oxidation and afforded a seco-aldehyde 22a and a dihydroxy derivative 23a in low yield. Hydrolysis of 22a followed by acid treatment afforded the furan 18. Hydrolysis of 23a gave a triol, which, on further oxidation, gave the aldehyde 16, the major product of the chromic acid oxidation of 1a.