Computational Design Of Enhanced Enantioselectivity In Chiral Phosphoric Acid-Catalyzed Oxidative Desymmetrization Of 1,3-Diol Acetals

A general method for the highly enantioselective desymmetrization of 2-alkyl-substituted 1,3-diols is presented. A combination of computational and experimental studies has been utilized to understand the origin of the stereocontrol of oxidative desymmetrization of 1,3-diol benzylideneacetals. DFT calculations demonstrate that the acetal protecting group is highly influential for high enantioselectivity, and a simple but effective new protecting group has been designed. The desymmetrization reactions proceed with high enantioselectivity for a variety of substrates. Moreover, the reaction conditions are also shown to be effective for desymmetrization of 2,2-dialkyl-substituted 1,3-diols, which provides chiral products bearing acyclic all-carbon quaternary stereocenters. The method has been applied to the formal synthesis of indoline alkaloids.