Other attributes
In one important reaction type, a main group organometallic compound of the type R-M (R = organic fragment, M = main group center) reacts with an organic halide of the type R'-X with formation of a new carbon-carbon bond in the product R-R'. The most common type of coupling reaction is the cross coupling reaction.[1][2][3]
Richard F. Heck, Ei-ichi Negishi, and Akira Suzuki were awarded the 2010 Nobel Prize in Chemistry for developing palladium-catalyzed cross coupling reactions.[4][5]
Broadly speaking, two types of coupling reactions are recognized:
Heterocouplings combine two different partners, such as in the Heck reaction of an alkene (RC=CH) and an alkyl halide (R'-X) to give a substituted alkene, or the Corey–House synthesis of an alkane by the reaction of a lithium diorganylcuprate (R2CuLi) with an organyl (pseudo)halide (R'X). Heterocouplings are also called cross-couplings.
Homocouplings couple two identical partners, as in the Glaser coupling of two acetylides (RC≡CH) to form a dialkyne (RC≡C-C≡CR).
Coupling reactions are illustrated by the famous Ullmann reaction:
An illustrative cross-coupling reaction is the Heck coupling of an alkene and an aryl halide:
