Biomimetic Synthesis of Chaxine and its Related Compounds.

The highly oxidized natural products chaxine B and BB have been synthesized from ergosterol in eight steps according to a route inspired by their proposed biosynthesis; key steps were an oxidative cascade from a furan intermediate to an enol ester using m-chloroperbenzoic acids (MCPBA), followed by diastereoselective epoxidation and acyloxy migration. This concise synthesis resulted in the revision of the structures of chaxine B and its naturally occurring analogs and syntheses of the unnatural analogues of these natural products for biological investigations.