Palladium-catalyzed coupling reactions: Difference between revisions

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	* ] between an organohalide and an ]		* ] between an organohalide and an ]
	* The ] of an aryl halide with an ]		* The ] of an aryl halide with an ]
			* The ] of an arenediazonium salt with an alkene

	Typical palladium catalysts used include the following compounds:		Typical palladium catalysts used include the following compounds:

Revision as of 20:27, 1 April 2011

Palladium compounds are used as a catalyst in many coupling reactions, usually as a homogeneous catalyst. Examples include:

Heck reaction between alkenes and aryl halides
Suzuki reaction between aryl halides and boronic acids
Stille reaction between organohalides and organotin compounds
Hiyama coupling between organohalides and organosilicon compounds
Sonogashira coupling between aryl halides and alkynes, with copper(I) iodide as a co-catalyst
Negishi coupling between an organohalide and an organozinc compound
The Buchwald-Hartwig amination of an aryl halide with an amine
The Heck-Matsuda Reaction of an arenediazonium salt with an alkene

Typical palladium catalysts used include the following compounds:

Unoptimized reactions typically use 10-15 mol% of palladium; where optimized, catalyst loadings can be on the order of 0.1 mol % or below. Many exotic ligands and chiral catalysts have been reported, but they are largely not available commercially, and do not find widespread use. Much work is being done on replacing the phosphine ligands with other classes, such as Arduengo-type carbene complexes, as the phosphine ligands are typically oxygen sensitive (easily oxidized), and are labile (requiring additional free ligands).

With these reactions becoming ubiquitous, there has been interest in better techniques for removing the palladium catalyst. Metal scavengers such as Smopex or resins such as QuadruPure and ISOLUTE promise more efficient separation than ordinary column chromatography.

In 2010, the Nobel Prize in Chemistry was awarded to Richard F. Heck, Ei-ichi Negishi and Akira Suzuki for their work on palladium-catalyzed cross couplings in organic synthesis.

References

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