Pd(OAc)2/1,1′-Methylene-3,3′-bis[(N-(isopropyl)imidazol-2-ylidene]: An Efficient Catalyst for the Heck Arylation of Various Olefins

The Mizoroki-Heck coupling reaction has been carried out using Pd(OAc)2 and bisimidazolium (1,1′-methylene-3,3′-bis[(N-(isopropyl)imidazol-2-ylidene]dibromide) for aryl bromides as well as less reactive chlorobenzene with mono- and di-substituted olefins. Only 0.025 mol% of Pd(II) shows a high activity toward the coupling reaction with turnover number (TON) ≈ 600-3960. Further, this catalyst system, Pd(OAc)2/Bisimidazolium, exhibits the excellent selectivity for the trans-isomer coupling products and the terminal arylation coupling products for mono- and di-substituted olefins, respectively. The nature of olefins (n-butyl acrylate, styrene, and 1,1-disubstituted olefins) has a significant contribution on the yield of the coupling products.