The Expedient Synthesis of 4,2‘-Difluoro-5‘-(7-trifluoromethyl- imidazo[1,2-a]pyrimidin-3-yl)biphenyl-2-carbonitrile, a GABA α2/3 Agonist

An expedient regioselective synthesis of a GABA α2/3 agonist 1 is described. The key step is an efficient regioselective palladium-catalyzed coupling of 7-trifluoromethylimidazo[1,2-a]pyrimidine (5) to 5‘-chloro-4,2‘-difluorobiphenyl-2-carbonitrile (15). The efficiency of this step was affected by the choice of solvent, ligand, and tetrabutylammonium salt additive.