Late-Stage Carbon Isotope Exchange of Aryl Nitriles through Ni-Catalyzed C-CN Bond Activation.

A facile one-pot strategy for CN and CN exchange with aryl, heteroaryl, and alkenyl nitriles using a Ni phosphine catalyst and BPh is described. This late-stage carbon isotope exchange (CIE) strategy employs labeled Zn(CN) to facilitate enrichment using the nonlabeled parent compound as the starting material, eliminating synthesis for precursor development. A broad substrate scope encompassing multiple pharmaceuticals is disclosed, including the preparation of [C] belzutifan to illustrate the exceptional functional group tolerance and utility of this labeling approach. Preliminary experimental and computational studies suggest the Lewis acid BPh is not critical for the oxidative addition step and instead plays a role in facilitating CN exchange on Ni. This CIE method dramatically reduces the synthetic steps and radioactive waste involved in preparation of C labeled tracers for clinical development.