Novel chiral thiourea organocatalysts for the catalytic asymmetric oxaziridination

Catalytic enantioselective oxaziridination is one of the challenging reactions in the oxidation of organic molecules. In this article, a series of novel chiral thiourea moleculars were synthesized from natural cinchona alkaloids and primary amines. By using these molecules as organocatalysts and m-chloroper-oxybenzoicacid (m-CPBA) as the oxidant, a methodology on highly enantioselective epoxidation of al-dimines has been developed. Several optically active oxaziridines have been constructed in good yields (up to 95%) and moderate to excellent enantioselectivities (up to 99% ee). A plausible transition state was also proposed. (C) 2015 Elsevier Ltd. All rights reserved.