Electron Donor-Acceptor Complex-Enabled Autoinductive Conversion of Acylnitromethanes to Acylnitrile Oxides in a Photochemical Machetti-De Sarlo Reaction: Synthesis of 5-Substituted 3-Acylisoxazoles.

A photochemical Machetti-De Sarlo reaction has been developed for preparing 5-substituted 3-acylisoxazoles from acylnitromethanes and terminal alkynes. This photochemical protocol utilizes an innovative electron donor-acceptor complex, generated in situ from acylnitromethanes, catalytic LiOtBu, and 1,1,1,3,3,3-hexafluoro-2-propanol, as a photosensitizer to promote rapid conversion with a broad substrate scope in up to 80% efficiency. A sigmoidal autoinductive kinetic profile is revealed, demonstrating the novel and unique dual catalysis in the first photochemical approach of this reaction.