Asymmetric α-hydroxylation of tetralone-derived β-ketoesters by using a guanidine-urea bifunctional organocatalyst in the presence of cumene hydroperoxide.

Highly enantioselective catalytic oxidation of 1-tetralone-derived β-keto esters was achieved by using a guanidine-urea bifunctional organocatalyst in the presence of cumene hydroperoxide (CHP), a safe, commercially available oxidant. The α-hydroxylation products were obtained in 99% yield with up to 95% enantiomeric excess (ee). The present oxidation was successfully applied to synthesize a key intermediate of the anti-cancer agent daunorubicin (2).