Asymmetric biomimetic oxidations of phenols: the mechanism of the diastereo- and enantioselective synthesis of thomasidioic acid.

Enantiopure chiral amidic derivatives of sinapic acid were oxidised with hydrogen peroxide using horseradish peroxidase (HRP) as the catalyst to give the aryltetraline dilignol thomasidioic acid. Trans-diastereoselectivity and enantioselectivity in the formation of thomasidioic acid was observed. Computational methods show that the enantioselectivity is controlled by the beta-beta oxidative coupling step, while the diastereoselectivity is controlled by the stability of the reactive conformation of the intermediate quinomethide.