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

Abstract

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⁻).