CuCN and Trimethylsilyl Chloride-Catalyzed Regiospecific Grignard Reactions to CF3-Containing Allylic Derivatives

CF₃-containing allylic alcohol derivatives were treated with an appropriate Grignard reagent in the presence of catalytic amounts of CuCN and trimethylsilyl chloride (TMSCl) to furnish products via the clean anti-S_N2′ mechanism. Experimental results as well as ab initio computational analyses unambiguously demonstrated the important roles of TMSCl as a Lewis basic additive for smooth promotion of reductive elimination and inhibition of the “Cu···F” elimination leading to undesired byproduct formation.