tBuOK/TMSOK-Mediated “Alkyl Halide to Alkyl Free Radical” Transformation for Transition-Metal-Free Benzoin α-C—H Alkylation

The alkali tert-butoxide (^tBuOK or ^tBuONa) mediated generation of aryl free radical from aryl iodide remarks a milestone discovery in the free radical chemistry. However, the equivalent “alkyl halide to alkyl free radical” transformation has not yet been realized in applicable synthesis by similar catalytic tactic. In this paper, the first practical “alkyl halide to alkyl free radical” transformation mediated by ^tBuOK or TMSOK in the direct α-C—H alkylation of benzoins is presented. As the parallelly significant issue as aryl free radical generation, the current work, while bringing a rather facile and useful new approach for the synthesis of diverse benzoins, represents also an important step in the alkyl free radical-based synthesis by displaying the higher generality of simple alkali base mediated radical formation.