Synthesis, structure and catalytic activity of a bimacrocylic NHC palladium allyl complex

The preparation of a bimacrocyclic NHC palladium allyl complex 4 is described. The complex was obtained by transmetalation with allyl palladium chloride dimer from the NHC silver complex 2 in 85% yield. Complex 4 was fully characterized by spectroscopic methods and by single-crystal X-ray analysis. In a preliminary catalytic study, complex 4 showed high activity in the Suzuki–Miyaura cross-coupling of unactivated aryl chlorides and bromides with 1-naphthalene-boronic acid at low catalyst loading. Good results were also obtained in the Mizoroki–Heck reaction of aryl bromides with styrene, but a decrease in yield was observed when aryl chlorides were used.