Photocatalytic Semireduction of Propiolamides in Microheterogeneous Solutions via Alkyne Radical Anions.

A photocatalytic protocol for generating alkyne radical anions from propiolamides in aqueous micellar solutions is reported. Using ascorbic acid and Ru(bpy)32+ under blue light, hydrated electrons mediate single-electron reduction. Alkyne radical anions undergo Z-selective semireduction or reductive hydroalkylation with styrenes. The method shows a broad scope, excellent functional group tolerance, and gram-scale scalability, replacing hazardous reagents and organic solvents with vitamin C and water.