Coupling reaction

In organic chemistry, a coupling reaction is a type of reaction in which two reactant molecules are bonded together. Such reactions often require the aid of a metal catalyst. In one important reaction type, a main group organometallic compound of the type R-M (where R = organic group, M = main group centre metal atom) 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.

Richard F. Heck, Ei-ichi Negishi, and Akira Suzuki were awarded the 2010 Nobel Prize in Chemistry for developing palladium-catalyzed cross coupling reactions.

Broadly speaking, two types of coupling reactions are recognized:

• Homocouplings joining two identical partners. The product is symmetrical
• Heterocouplings joining two different partners. These reactions are also called cross-coupling reactions. The product is unsymmetrical, .

Homo-coupling types

Coupling reactions are illustrated by the Ullmann reaction:

Reaction		Year	Organic compound		Coupler		Remark
Wurtz reaction	1855
Pinacol coupling reaction	1859
Glaser coupling	1869
Ullmann reaction	1901
Fittig reaction
Scholl reaction	1910

Cross-coupling types

Main article: Cross-coupling reaction

Reaction		Year	Reactant A	Reactant B		Catalyst		Remark
Grignard reaction	1900	R-MgBr
Gomberg–Bachmann reaction	1924	Ar-H
Cadiot–Chodkiewicz coupling	1957	RC≡CH
Castro–Stephens coupling	1963	RC≡CH
Corey–House synthesis	1967	R2CuLi or RMgX
Cassar reaction	1970	Alkene
Kumada coupling	1972	Ar-MgBr
Heck reaction	1972	alkene
Sonogashira coupling	1975	RC≡CH
Murahashi coupling	1975	RLi
Negishi coupling	1977	R-Zn-X
Stille reaction	1978	R-SnR3
Suzuki reaction	1979	R-B(OR)2
Hiyama coupling	1988	R-SiR3
Buchwald–Hartwig amination	1994	R2N-H
Fukuyama coupling	1998	R-Zn-I
Liebeskind–Srogl coupling	2000	R-B(OR)2
(Li) Cross dehydrogenative coupling(CDC)	2004	R-H
Wurtz–Fittig reaction	1864	R-X