hydrovinylation
{{Short description|Organic reaction which inserts an alkene into a C-H bond of ethylene}}
In organic chemistry, hydrovinylation is the formal insertion of an alkene into the C-H bond of ethylene ({{chem2|H2C\dCH2}}):
:{{chem2|CH2\dCHR + CH2\dCH2 -> CH3\sCHR\sCH\dCH2}}
The more general reaction, hydroalkenylation, is the formal insertion of an alkene into the C-H bond of any terminal alkene. The reaction is catalyzed by metal complexes. A representative reaction is the conversion of styrene and ethylene to 3-phenybutene:{{cite encyclopedia |encyclopedia=Comprehensive Organic Synthesis II (Second Edition)|title=Hydrovinylation Reactions in Organic Synthesis|author=T. V. RajanBabu |author2=G. A. Cox |doi=10.1016/B978-0-08-097742-3.00533-4|year=2014|pages=1582–1620|volume=5|chapter=5.32 Hydrovinylation Reactions in Organic Synthesis|isbn=978-0-08-097743-0}}
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Ethylene dimerization
The dimerization of ethylene which gives 1-butene is another example of a hydrovinylation. In the Dimersol and Alphabutol Processes, alkenes are dimerized for the production of gasoline and for comonomers such as 1-butene. These processes operate at several refineries across the world at the scales of about 400,000 tons/year (2006 report).{{cite journal|title=Olefin Metathesis: The Early Days (Nobel Lecture)|author=Yves Chauvin|year=2006|doi=10.1002/anie.200601234|pmid=16724296|journal=Angew. Chem. Int. Ed.|volume=45|issue=23|pages=3740–3747|author-link=Yves Chauvin}} 1-Butene is amenable to isomerization to 2-butenes, which is used in olefin conversion technology to give propylene.
In organic synthesis
The addition can be done highly regio- and stereoselectively, although the choices of metal, ligands, and counterions often play very important role. Many metals have also been demonstrated to form active catalysts, including nickel{{cite journal | author = Ho, C.-Y. |author2=He, L. | year = 2010 | pages = 9182–9186 | title = Catalytic Intermolecular Tail-to-Tail Hydroalkenylation of Styrenes with alpha-Olefins: Regioselective Migratory Insertion Controlled by a Nickel/N-Heterocyclic Carbene | issue = 48 | pmid = 20853303 | journal = Angew. Chem. Int. Ed. | volume = 49 | doi = 10.1002/anie.201001849 }}{{cite journal | author = Ho, C.-Y. |author2=He, L. | year = 2012 | pages = 1481–1483 | title = Shuffle Off the Classic Beta-Si Elimination by Ni-NHC Cooperation: Implication for C–C Forming Reactions Involving Ni-Alkyl-Beta-Silanes | issue = 10 | pmid = 22116100 | journal = Chem. Commun. | volume = 48 | doi = 10.1039/c1cc14593b }}{{cite journal |doi=10.15227/orgsyn.085.0248 |title=(R)-3-Methyl-3-Phenyl-1-Pentene Via Catalytic Asymmetric Hydrovinylation |journal=Organic Syntheses |date=2008 |volume=85 |pmid=19672483 |last1=Smith |first1=C. R. |last2=Zhang |first2=A. |last3=Mans |first3=D. J. |last4=Rajanbabu |first4=T. V. |pages=248–266 |pmc=2723857 }} and cobalt.{{cite journal | author = Grutters, M. M. P. |author2=Muller, C. |author3=Vogt, D. | year = 2006 | pages = 7414–5 | title = Highly Selective Cobalt-Catalyzed Hydrovinylation of Styrene | issue = 23 | pmid = 16756275| journal = J. Am. Chem. Soc. | volume = 128 | doi = 10.1021/ja058095y }}{{cite journal | author = Hilt, G. |author2=Danz, M. |author3=Treutwein, J. | year = 2009 | pages = 3322–5 | title = Cobalt-Catalyzed 1,4-Hydrovinylation of Styrenes and 1-Aryl-1,3-butadienes | issue = 15 | pmid = 19583205 | journal = Org. Lett. | volume = 11 | doi = 10.1021/ol901064p }}{{cite journal | author = Sharma, R. K. |author2=RajanBabu, T. V. | year = 2010 | pages = 3295–7 | title = Asymmetric Hydrovinylation of Unactivated Linear 1,3-Dienes | issue = 10 | pmid = 20163120| journal = J. Am. Chem. Soc. | pmc = 2836389 | volume = 132 | doi = 10.1021/ja1004703 }}
In a stoichiometric version of a hydrovinylation reaction, nucleophiles add to an electrophilic transition metal alkene complex, forming a C-C bond. The resulting metal alkyl undergoes beta-hydride elimination, liberating the vinylated product.{{cite journal |doi=10.15227/orgsyn.066.0095|title=Vinylation of Enolates with a Vinyl Cation Equivalent: trans-3-Methyl-2-Vinylcyclohexanone |journal=Organic Syntheses |year=1988 |volume=66 |page=95|author=Tony C. T. Chang, Myron Rosenblum, Nancy Simms }}
Hydroarylation
Hydroarylation is again a special case of hydrovinylation. Hydroarylation has been demonstrated for alkyne and alkene substrates. An early example was provided by the Murai reaction, which involves the insertion of alkenes into a C-H bond of acetophenone. The keto group directs the regiochemistry, stabilizing an aryl intermediate.{{Cite journal|last1=Murai|first1=Shinji|last2=Kakiuchi|first2=Fumitoshi|last3=Sekine|first3=Shinya|last4=Tanaka|first4=Yasuo|last5=Kamatani|first5=Asayuki|last6=Sonoda|first6=Motohiro|last7=Chatani|first7=Naoto|date=1993-12-09|title=Efficient catalytic addition of aromatic carbon-hydrogen bonds to olefins|journal=Nature|language=en|volume=366|issue=6455|pages=529–531|doi=10.1038/366529a0|bibcode=1993Natur.366..529M|s2cid=5627826}}
File:Figure_1._General_scheme_of_a_Murai_reaction.png
When catalyzed by palladium carboxylates, a key step is electrophilic aromatic substitution to give a Pd(II) aryl intermediate.{{cite journal|author1=Jia, C. |author2=Kitamura, T. |author3=Fujiwara, Y. |title=Catalytic Functionalization of Arenes and Alkanes Via C-H Bond Activation|journal=Acc. Chem. Res.|year=2001|volume=34|issue=8|pages=633–639|doi=10.1021/ar000209h|pmid=11513570}} Gold behaves similarly.{{cite journal |doi=10.1016/j.tet.2008.01.081|title=Recent advances in syntheses of heterocycles and carbocycles via homogeneous gold catalysis. Part 1: Heteroatom addition and hydroarylation reactions of alkynes, allenes, and alkenes|year=2008|last1=Shen|first1=Hong C.|journal=Tetrahedron|volume=64|issue=18|pages=3885–3903}} Hydropyridination is a similar reaction, but entails addition of a pyridyl-H bond to alkenes and alkynes.{{cite journal |doi=10.1021/acs.organomet.5b01021|title=Chromium-Catalyzed Regioselective Hydropyridination of Styrenes|year=2016|last1=Li|first1=Yuexuan|last2=Deng|first2=Gongda|last3=Zeng|first3=Xiaoming|journal=Organometallics|volume=35|issue=5|pages=747–750}}
See also
- Vinylation, the process of affixing a vinyl group