lmidazole-coordinated monodentate NHC-Pd(II) complex derived from proline and its application to the coupling reaction of arylboronic acids with carboxylic acid anhydrides in water at room temperature

Cleavage of a C-N bond of imidazolium salt derived from N-phenyl-substituted proline was observed in this laboratory. A novel imidazole-coordinated monodentate NHC-Pd(II) complex 5 was obtained as the sole product in good yield in the reaction of imidazolium salt 4 with Pd(OAc)(2) in refluxing THF. The structure of complex 5 was determined unambiguously by an X-ray diffraction. The complex was found to be a good catalyst in the cross-coupling reaction of arylboronic acids with carboxylic acid anhydrides in water at room temperature. Copyright (C) 2011 John Wiley & Sons, Ltd.