Photoredox‐Enabled Self‐(3+2) Cyclization of Vinyldiazo Reagents: Synthesis of Cyclopentenyl α‐Diazo Compounds

A photocatalytic self-(3+2) cycloaddition of vinyldiazo compounds is described, which provides cyclopentene derivatives with conservation of one diazo functional group. Experimental insights and density functional theory indicate that the reaction is triggered by an unusual single electron oxidation of vinyldiazo compounds, while the photolysis for the generation of free carbene species is not involved. The synthetic applications of the resulting cyclopentenyl α-diazo compounds were demonstrated based on the rich chemistry of the diazo functional group.