Synthesis of Ventilagone

Abstract

Synthesis of ventilagone (4) from the naphthol (5) was complicated by oxidation involving the central ring and by extensive epimerization to the trans series in the course of Lewis-acid-mediated demethylation . These complications were avoided by prior protection as the acetate (23). Oxidative demethylation and subsequent hydrolysis converted the latter into the dihydroxy quinone (6), which was also accessible from the nitro compound (26). Spectroscopic procedures for determining relative stereochemistry of such systems are discussed. Compound (6) underwent radical C-methylation to give ventilagone (4).