Site- and Stereoselective C–H Alkylations of Carbohydrates Enabled by Cooperative Photoredox, Hydrogen Atom Transfer, and Organotin Catalysis
Daniel J. Gorelik, Julia A. Turner, Tarunpreet Singh Virk, Daniel A. Foucher, Mark S. Taylor
Abstract
Diorganotin dihalides act as cocatalysts for site-selective and stereoselective couplings of diol-containing carbohydrates with electron-deficient alkenes in the presence of an Ir(III) photoredox catalyst and quinuclidine, a hydrogen atom transfer mediator. Quantum-chemical calculations support a proposed mechanism involving the formation of a cyclic stannylene acetal intermediate that shows enhanced reactivity toward hydrogen atom abstraction by the quinuclidinium radical cation. Addition of the carbon-centered radical to the alkene partner results in C-alkylation of the carbohydrate substrate.
Topics & Concepts
ChemistryHydrogen atomHydrogen atom abstractionReactivity (psychology)AlkeneStereoselectivityCatalysisAlkylationPhotochemistryQuinuclidineAcetalMedicinal chemistryStereochemistrySubstrate (aquarium)DiolHydrogenOrganic chemistryAlkylAlternative medicineMedicineGeologyPathologyOceanographyRadical Photochemical ReactionsSulfur-Based Synthesis TechniquesCatalytic C–H Functionalization Methods