Chemoenzymatic Synthesis of Enantiomerically Pure syn‐Configured 1‐Aryl‐3‐methylisochroman Derivatives

Abstract

AbstractA two‐step synthesis of various enantiomerically pure 1‐aryl‐3‐methylisochroman derivatives was accomplished through asymmetric biocatalytic ketone reduction followed by an oxa‐Pictet–Spengler reaction. The compounds were obtained in good to excellent yield (47–92 %) in favor of the syn diastereomers [dr (syn/anti) up to 99:1]. Enantiopure arylpropanols serving as pronucleophiles for the C–C bond‐formation step were obtained by biocatalytic reduction by employing enantiocomplementary alcohol dehydrogenases, which gave access to the (S) and (R) enantiomer with up to >99 % conversion and up to >99 % ee.