A Radical Addition Approach to a Heptafluoroisopropyl Substituted Arene, Combined with a Highly Diastereoselective Annulation Reaction To Synthesize the Tricyclic Core of BMS-986251

We have devised an asymmetric route to the tricyclic core 10 of BMS-986251. The six-step synthesis utilizes readily available starting materials, involves the one-step installation of the perfluoro isopropyl moiety through a radical mechanism, and leverages a novel diastereoselective annulation to build the pyrrolidine ring. Overall, 10 was obtained in 49% yield as a single stereoisomer in 6 steps and 3 isolations using this new route.