A computational study of C–H bond abstraction in β-Amino Alcohols: O side activation over N-side via boronate adduct formation

Abstract A Density Functional Theory (DFT) study was performed to evaluate the reaction mechanism underlying the chemoselective C–H abstraction in β-amino alcohols under a photoredox-catalyzed platform. Our results support a three-step mechanism based on the formation of a highly activated tetracoordinated boronate adduct followed by a selective hydrogen atom transfer (HAT) and a Giese-type radical addition, which together generate the experimentally observed γ-oxo-δ-amino esters. We demonstrated that α-hydroxy C–H bonds are more readily activated towards the HAT step than the α-amino C–H bond. This enhanced chemoselectivity arises from the tetracoordinated boronate adduct, which increases the hydridic character of the α-hydroxy H atom and lowers the bond dissociation energy (BDE) of the C–H bond.