Hiyama coupling
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2008-06-25T15:33:35Z
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In [[organic chemistry]], a '''Hiyama coupling''' is a [[palladium]] or [[nickel]]-catalyzed [[cross coupling reaction]] of [[organosilicon|organosilane]]s with [[Organic compound|organic]] [[halides]] or [[triflate]]s. Hiyama couplings were first reported by Yasuo Hatanaka and Tamejiro Hiyama in [[1988]] <ref>''Cross-coupling of organosilanes with organic halides mediated by a palladium catalyst and tris(diethylamino)sulfonium difluorotrimethylsilicate'' Yasuo Hatanaka, Tamejiro Hiyama [[J. Org. Chem.]]; '''1988'''; 53(4); 918-920. {{DOI|10.1021/jo00239a056}}</ref>.
Typically, the Hiyama coupling reaction is promoted by activation of the organosilane with [[fluoride]]s. The reaction possesses many advantages such as low environmental impact, high [[atom efficiency]], and safe handling compared with the coupling reactions of [[Organoborane|organoboron]], [[organozinc]], or [[organotin]] compounds.
In the original 1988 publication 1-iodonaphthalene was reacted with trimethylvinylsilane to 1-vinylnaphthalene with catalyst the [[allylpalladium chloride dimer]] dissolved in [[HMPA]] and [[TASF reagent]] as fluorine source.
:[[Image:Hiyama coupling.png|500px|Hiyama coupling]]
The reaction proceeds through the usual [[oxidative addition]] , [[transmetalation]], [[trans-cis isomerization]] and [[reductive elimination]] sequence. The purpose of the fluorine is to activate the silicon compound RSiR'<sub>3</sub> to a RSi<sup>-</sup>R'<sub>3</sub>F intermediate which is more amiable to transmetalation. Without the added fluorine the organosilicon compound is simply too stable.
In one extension the alkenylsilane is prepared [[in situ]] from a terminal [[alkyne]] and [[tetramethyldisiloxane]] <ref>[[Organic Syntheses]], Vol. 81, p.54 ('''2005'''). [http://www.orgsynth.org/orgsyn/pdfs/v81p0054.pdf Link]</ref> or [[hexamethylcyclotrisiloxane]] <ref>[[Organic Syntheses]], Vol. 81, p.42 ('''2005'''). [http://www.orgsynth.org/orgsyn/pdfs/v81p0042.pdf Link]</ref>.
In another extension the reaction is assisted by [[nickel chloride]], [[LiHMDS]] and [[norephedrine]] with [[caesium fluoride]] as fluorine donor <ref>''Hiyama Reactions of Activated and Unactivated Secondary Alkyl Halides Catalyzed by a Nickel/Norephedrine Complex'' Neil A. Strotman, Stefan Sommer, and Gregory C. Fu [[Angew. Chem. Int. Ed.]] '''2007''', 46, 3556 –3558 {{DOI|10.1002/anie.200700440}}</ref>:
:[[Image:HiyamaCouplingExtension.png|400px|Hiyama reaction extension Strotman 2007]]
==See also==
*[[Coupling reaction]]
*[[Organometallic chemistry]]
==References==
{{reflist}}
[[Category:Organometallic chemistry]]
[[Category:Carbon-carbon bond forming reactions]]
[[Category:Palladium]]
[[Category:Name reactions]]