CATALYST SYSTEM COMPRISING TRANSITION METAL AND IMIDAZOLINE-2-YLIDENE OR IMIDAZOLIDINE-2-YLIDENE AND ITS USE IN COUPLING REACTIONS

摘要

This invention provides a process for conducting reactions to form carbon-to-carbon or carbon-to-nitrogen bonds. The processes of the present invention make use of N-heterocyclic carbenes as ancillary ligands in various types of couplings of aryl halides and/or aryl pseudohalides. A Suzuki coupling, for example, can be carried out by mixing, in a liquid medium, at least one strong base; at least one aryl halide or aryl pseudohalide in which all substituents are other than boronic acid groups, wherein the aryl halide has, directly bonded to the aromatic ring(s), at least one halogen atom selected from the group consisting of a chlorine atom, a bromine atom, and an iodine atom; at least one arylboronic acid in which all substituents are other than chlorine atoms, bromine atoms, iodine atoms, or pseudohalide groups; at least one metal compound comprising at least one metal atom selected from nickel, palladium, and platinum, wherein the formal oxidation state of the metal is zero or two; and at least one N-heterocyclic carbene. One preferred type of N-heterocyclic carbene is an imidazoline-2-ylidene of the formula (I) wherein R<1> and R<2> are each, independently, alkyl or aryl groups having at least 3 carbon atoms, R<3> and R<4> are each, independently, a hydrogen atom, a halogen atom, or a hydrocarbyl group.