| abstract |
This invention provides a catalyst system useful in many coupling reactions, such as Suzuki, Kumada, Heck, and amination reactions. The catalyst system of the present invention makes use of N-heterocyclic carbenes or their protonated salts. The composition of the catalyst system comprises at least one transition metal compound and at least one N-heterocyclic carbene or its protonated salt. This invention further provides novel N-heterocyclic carbenes and their protonated salts. One type of N-heterocyclic carbene used in this invention is an imidazolinc-2-ylidene wherein the 1 and 3 positions are each, independently, substituted by an aromatic group in which each ortho position is, independently, substituted by a secondary or tertiary group which has at least three atoms. |