O-Alkylisourea-Enabled Nickel/Photoredox-Catalyzed Giese Reaction.

The Giese reaction is one of the most widely employed carbon-carbon (C-C) bond-forming reactions in synthetic chemistry. In particular, the generation of alkyl radicals via photocatalytic deoxygenation of alcohols under mild conditions is synthetically appealing. Herein, we report an efficient nickel/photoredox-catalyzed Giese reaction of alcohol-derived O-alkylisoureas with a range of Michael acceptors, using an inexpensive diaryl ketone as the photocatalyst. Notably, the system successfully transforms secondary, tertiary, and especially primary alcohols into the target products in moderate to good yields. Mechanistic studies suggest that the formation of an alkyl halide intermediate, via nucleophilic substitution of the O-alkylisourea with the nickel catalyst, is the key step for radical generation.