Organocatalytic Michael Addition of Naphthoquinone with α,β-Unsaturated Ketones: Primary Amine Catalyzed Asymmetric Synthesis of Lapachol Analogues

A highly efficient organocatalytic synthesis of lapachol analogues from the Michael addition of naphthoquinone to various alpha,beta-unsaturated ketones catalyzed by primary amines is presented. Good to high yields (up to 93%) and high to excellent enantioselectivities (up to 98% ee) were obtained for the target compounds. MS (ESI) provided evidence for the key intermediates in the proposed mechanism.