Gold Phosphole Complexes as Efficient Catalysts for Alkyne Activation

Abstract

Gold(I) complexes bearing monophosphole ligands were synthesized, and their electronic and steric properties were compared to those of their triphenylphosphine-based counterparts. Cationic phosphole-based gold(I) complexes are active and selective in enyne cycloisomerization and in olefin cyclopropanation, with a good correlation between the ligand σ-donor ability and the catalytic activity. For the most efficient ligand, 1-phenyl-2,3,4,5-tetramethylphosphole (TMP), a highly active, selective, and stable cationic [Au(TMP)(CH3CN)]SbF6 complex was isolated.