Donor-Acceptor Complex Enables Alkoxyl Radical Generation for Metal-Free C(sp )-C(sp ) Cleavage and Allylation/Alkenylation.

The alkoxyl radical is an essential and prevalent reactive intermediate for chemical and biological studies. Here we report the first donor-acceptor complex-enabled alkoxyl radical generation under metal-free reaction conditions induced by visible light. Hantzsch ester forms the key donor-acceptor complex with N-alkoxyl derivatives, which is elucidated by a series of spectrometry and mechanistic experiments. Selective C(sp )-C(sp ) bond cleavage and allylation/alkenylation is demonstrated for the first time using this photocatalyst-free approach with linear primary, secondary, and tertiary alkoxyl radicals.