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

Abstract 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 α‐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 enantiopreferences. 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.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)