Palladium-catalyzed coupling reactions: Difference between revisions

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	* ] between aryl halides and ]s, with ] as a co-catalyst		* ] between aryl halides and ]s, with ] as a co-catalyst
	* The ] of an aryl halide with an ]		* The ] of an aryl halide with an ]
			* The ] of ] and aryl or vinyl halides
	* The ] of an arenediazonium salt with an alkene		* The ] of an arenediazonium salt with an alkene

Revision as of 23:49, 30 December 2014

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

Negishi coupling between an organohalide and an organozinc compound
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
The Buchwald-Hartwig amination of an aryl halide with an amine
The Kumada coupling of grignards and aryl or vinyl halides
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 SiliCycle's SiliaMetS, 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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