Early Transition Metal-Catalyzed Cross-Coupling Reaction of Aryl Fluorides with a Phenethyl Grignard Reagent Accompanied by Rearrangement of the Phenethyl Group

Abstract

Defluorination of 1-fluoronaphthalene was catalyzed by CpTiCl 3 and an alkyl Grignard reagent system. The reaction of 1-fluoronaphthalene, however, with 3 equiv of phenethylmagnesium chloride in the presence of a catalytic amount of transition metal catalysts afforded 1-(1-phenethyl)naphthalene in good yield via isomerization of the phenethyl group. Among the examined catalysts, CpTiCl 3 and TaCl 5 showed much higher activity than the others. The similar coupling reactions of phenethylmagnesium chloride with substituted fluoroarenes proceeded with high regioselectivity at the para -position to produce the corresponding 1-phenethylarenes in good yields.