Semi-syntheses of the 11-hydroxyrotenoids sumatrol and villosinol

We describe semi-syntheses of the 11-hydroxyrotenoids sumatrol (1) and villosinol (2), starting from rotenone (5), using an oxime-directed C11–H functionalisation approach. Thus, rotenone (5) was converted into rotenone oxime (6), which gave dimeric palladacycle 7 following reaction with Na2PdCl4·3H2O. Controlled, divergent, oxidation of palladacycle 7 with either Pb(OAc)4 or K2Cr2O7 afforded the 11-acetoxylated intermediates 9 and 13, respectively, which were transformed into sumatrol (1) and villosinol (2).