Cooperative Catalytic Coupling of Benzyl Chlorides and Bromides with Electron-Deficient Alkenes

Benzyl radicals are an important class of intermediate.
The use
of visible light to generate them directly from their respective halides
is an ideal synthetic strategy. The central impediment associated
with their direct single-electron reduction (photo- or electro-) lies
in their highly variable and structurally dependent reduction potential,
which combine to make the identification of a general set of conditions
difficult. Herein, we have employed a strategy of nucleophilic cooperative
catalysis in which catalytic lutidine undergoes halide substitution,
which decreases and levels the reduction potential. This allows a
general set of photocatalytic conditions to transform a broad range
of benzyl halides into radicals that can be used in the synthesis
of more complex molecules, exemplified here by Giese coupling with
electron-deficient alkenes.