N-Heterocyclic Carbene-Rhodium(I) Complexes Derived from Proline for the 1,4-Conjugate Addition of Arylboronic Acids to Enones in Neat Water

N-Heterocyclic carbene-rhodium(I) complexes derived from N-benzyl substituted proline have been successfully synthesized and were found to be efficient catalysts for the 1,4-conjugate addition of arylboronic acids to enones in neat water at 40 A degrees C. Under the optimal reaction conditions, all reactions gave the addition products in good to high yields.