Ti-Catalyzed Functional Group Tolerant and Regioselective Cross Couplings of (Hetero)aryl Grignard Reagents with Halopyridines

We report an unprecedented Ti-catalyzed functional group tolerant and regioselective coupling reaction where (hetro)­aryl Grignard reagents are coupled with halopyridines and haloquinolines through an S_RN pathway. A simple titanate catalyst not only triggered radical anion generation and the corresponding S_RN couplings but also enabled high functional group tolerance and regioselectivity. Highly electron-deficient functionalized Grignard reagents were quite involved in such reactions, and a variety of valuable arylpyridines, bipyridines, and terpyridines were assembled facilely.