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 -keto esters was achieved by using a guanidine-urea bifunctional organocatalyst in the presence of cumene hydroperoxide (CHP), a safe, commercially available oxidant. The -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).