Photocatalytic streamlined dual-functional group transfer from cyanopyridine to internal alkynes

The streamlined dual-functional group transfer (streamlined dual-FGT) strategy represents an efficient and sustainable approach for difunctionalization reactions, where all atoms or functional groups from the starting materials are fully incorporated into the final products without generating by-products. Pyridine and nitrile functionalities are prevalent and highly valued structural motifs found in a myriad of natural products, pharmaceuticals, agrochemicals, and polymers. The simultaneous incorporation of these groups via the streamlined dual-FGT strategy is thus of considerable significance in synthetic chemistry. Herein, we report a regioselective pyridylcyanation of internal alkynes enabled by an oxalate-based photocatalytic system, employing cyanopyridine as a streamlined dual-functional group transfer reagent. Mechanistic investigations using time-resolved spectroscopy reveal that the transformation proceeds through a photoinduced regioselective radical addition of the persistent cyanopyridine radical anion to alkynes, followed by the cooperative release and re-addition of the cyanide ion (CN⁻). The streamlined dual-functional group transfer strategy represents an efficient and sustainable approach for difunctionalization reactions, where all atoms or functional groups from the starting materials are fully incorporated into the final products. Herein, the authors report a regioselective pyridylcyanation of internal alkynes enabled by an oxalate-based photocatalytic system, employing cyanopyridine as a streamlined dual-functional group transfer reagent.