Heck Reaction Using a New N-Heterocyclic Carbene Palladium Complex on Silica

Significance

Heck reaction of bromobenzene with methylacrylate was examined with a new reusable N-heterocyclic carbene (NHC) palladium complex/ionic liquid matrix immobilized on a silica support. Thus, the reaction of N-methylimidazole with (3-chloropropyl)trimethoxysilane gave the ionic liquid matrix N-3-(3-trimethoxylsilylpropyl)-3-methyl imidazolium chloride (1). A sub-stoichiometric amount of Pd(OAc)₂ reacted with 1 to give NHC-Pd complex 2, which reacted with SiO₂ to form the covalently anchored NHC-Pd/ionic liquid (IL) matrix system 3. The Heck reaction of bromobenzene with methylacrylate in the presence of silica-supported NHC-Pd/IL 3 in NMP gave the methyl 3-phenylacrylate in 95% yield. The catalyst was readily recovered and reused several times without any loss of catalytic activity (average: 91% yield).