Cross-Coupling Reactions

A cross-coupling reaction in organic chemistry occurs when two fragments are combined with the help of a metal catalyst. A main group organometallic compound of type R-M (R = organic fragment, M = main group centre) combines with an organic halide of type R'-X in one significant reaction type, producing the product R-R', which forms a new carbon-carbon bond. A subset of coupling reactions are cross-coupling reactions. In arylations, it is often employed. Richard F. Heck, Ei-ichi Negishi, and Akira Suzuki were awarded the 2010 Nobel Prize in Chemistry for developing palladium-catalyzed coupling reactions. On a metal complex of the form LnMR(R'), the organic substituents R and R' are typically eliminated using reductive means (where L is some arbitrary spectator ligand). From a low valence precursor Ln, the critical intermediate LnMR(R') is created in two steps. LnMR is produced when an organic halide (RX) is added oxidatively to LnM. (X). After that, a source of R' is used to transmetallate the second partner. Reductive elimination of the two coupling fragments is the last step, which regenerates the catalyst and produces the organic product. Unsaturated substrates, including C(sp)X and C(sp2)X bonds, pair more readily in part because they contribute to the catalyst more quickly.