Polarity Umpolung Strategy for the Radical Alkylation of Alkenes

Abstract

Free radical mediated alkylation of alkenes is a challenging and largely unmet goal. Disclosed here is a conceptually novel "polarity umpolung" strategy for radical alkylation of alkenes using a portfolio of easily accessed, difunctional alkylating reagents. This strategy is achieved by substituting inherently nucleophilic alkyl radicals with electrophilic sulfone-bearing surrogates, thus inverting the usual mode of reactivity. Along with alkylation, either an heteroaryl or oximino group is concurrently incorporated into the alkenes by a consecutive docking and migration process, leading to valuable products. The reaction displays a broad functional-group tolerance under mild reaction conditions. The protocol opens new vistas for the late-stage modification of complex natural products and drug molecules containing alkene moieties.

Keywords: alkenes; heterocycles; photochemistry; radicals; umpolung.