Synthesis of 6, 9-Bisnormethyl-8-methoxy-12, 13-epoxy-6, 8, 10-trichothecatriene

An efficient synthesis of an A-ring aromatic trichothecane analogue, 6, 9-bisnormethyl-8-methoxy-12,13-epoxy-6, 8, 10-trichothecatriene (11), has been developed. The aryl allyl ether, 2, was converted in a series of six steps to 7b in ca. 74% overall yield. Bromination of the enolate anion of 7b, removal of the benzyl protecting group, and cyclization (sodium hydride in ether) gave the tricyclic ketone, 9, in very high yield. Alternatively, hydrogenolysis of 7b followed by acetylation and bromination gave 13c. Treatment of 13c with DBN gave 9. The spiro epoxide. 11, was prepared from 9 by treatment with dimethylsulfonium methylide.