Extremely Efficient Cross-Coupling of Benzylic Halides with Aryltitanium Tris(isopropoxide) Catalyzed by Low Loadings of a Simple Palladium(II) Acetate/Tris(p-tolyl)phosphine System

Highly efficient coupling reactions of benzylic bromides or chlorides with aryltitanium tris(isopropoxide) [ArTi(O-i-Pr)(3)] catalyzed by a simple palladium(II) acetate/tris(p-tolyl)phosphine [Pd(OAc)(2)/P(p-tolyl)(3)] system are reported. The coupling reactions proceed in general at room temperature employing low catalyst loadings of 0.02 to 0.2 mol%, affording coupling products in excellent yields of up to 99%. For benzylic bromides bearing strong electron-withdrawing cyano (CN) or trifluoromethyl (CF3) substituents, the reactions require a higher catalyst loading of 1 mol%, or the reactions are carried out at 60 degrees C. The catalytic system also tolerates (1-bromoethyl)benzene bearing beta-hydrogen atoms while using a catalyst loading of 1 mol% to afford the coupling product in a 70% yield.