Enantiocomplementary Chemoenzymatic Asymmetric Synthesis of (R)- and (S)-Chromanemethanol

A non-lipase-based, enantiocomplementary chemoenzymatic route towards enantiopure (R)- and (S)-chromanemethanol (12), which are the key building blocks for the synthesis of stereoisomerically pure alpha-tocopherols, has been achieved by the biocatalytic resolution of a racemic 2,2-disubstituted oxirane using an epoxide hydrolase and a halohydrin dehalogenase, which exhibit opposite enantio-preferences. The introduction of chirality at an early stage of the synthesis ensured a high efficiency, leading to total overall yields of 16 and 26% for (R)- and (S)-chromanemethanol (12), respectively. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)