ortho-Directed metallation in the regiocontrolled synthesis of enantiopure 2- and/or 3-substituted (S)S-(p-tolylsulfinyl)-1,4-benzoquinones

Abstract Enantiomerically pure (S) S -( p -tolylsulfinyl)-1,4-benzoquinones with alkyl and methoxy substituents at C-2 and/or C-3 are synthesized by CAN oxidation of adequately substituted (S) S -( p -tolylsulfinyl)-1,4-dimethoxyaromatic precursors 2 or 3 . These compounds were obtained by ortho -directed metallation or bromo-metal exchange from the corresponding p -methoxyanisoles in a highly regiocontrolled manner.