Highly Efficient Heck Reactions of Aryl Bromides with n-Butyl Acrylate Mediated by a Palladium/Phosphine−Imidazolium Salt System

A new phosphine−imidazolium salt, L·HBr (1, L = (1-ethylenediphenylphosphino-3-(mesityl))imidazol-2-ylidene), has been prepared. A combination of 0.5 mol % of Pd(dba)₂ and 0.5 mol % of L·HBr in the presence of 2 equiv of Cs₂CO₃ as base has proven to be highly efficient in the Heck coupling reactions of aryl bromides (from electron-deficient to electron-rich aryl bromides) with n-butyl acrylate.