Hydrovinylation

In organic chemistry, hydrovinylation is the formal insertion of an alkene into the C-H bond of ethylene (H2C=CH2):

CH2=CHR + CH2=CH2 → CH3−CHR−CH=CH2

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:[1]

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).[2] 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[3][4][5] and cobalt.[6][7][8]

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.[9]

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.[10]

A Murai reaction (X = directing group, typically X = O).

When catalyzed by palladium carboxylates, a key step is electrophilic aromatic substitution to give a Pd(II) aryl intermediate.[11] Gold behaves similarly.[12] Hydropyridination is a similar reaction, but entails addition of a pyridyl-H bond to alkenes and alkynes.[13]

See also

References

  1. ^ T. V. RajanBabu; G. A. Cox (2014). "5.32 Hydrovinylation Reactions in Organic Synthesis". Hydrovinylation Reactions in Organic Synthesis. Comprehensive Organic Synthesis II (Second Edition). Vol. 5. pp. 1582–1620. doi:10.1016/B978-0-08-097742-3.00533-4. ISBN 978-0-08-097743-0.
  2. ^ Yves Chauvin (2006). "Olefin Metathesis: The Early Days (Nobel Lecture)". Angew. Chem. Int. Ed. 45 (23): 3740–3747. doi:10.1002/anie.200601234. PMID 16724296.
  3. ^ Ho, C.-Y.; He, L. (2010). "Catalytic Intermolecular Tail-to-Tail Hydroalkenylation of Styrenes with alpha-Olefins: Regioselective Migratory Insertion Controlled by a Nickel/N-Heterocyclic Carbene". Angew. Chem. Int. Ed. 49 (48): 9182–9186. doi:10.1002/anie.201001849. PMID 20853303.
  4. ^ Ho, C.-Y.; He, L. (2012). "Shuffle Off the Classic Beta-Si Elimination by Ni-NHC Cooperation: Implication for C–C Forming Reactions Involving Ni-Alkyl-Beta-Silanes". Chem. Commun. 48 (10): 1481–1483. doi:10.1039/c1cc14593b. PMID 22116100.
  5. ^ Smith, C. R.; Zhang, A.; Mans, D. J.; Rajanbabu, T. V. (2008). "(R)-3-Methyl-3-Phenyl-1-Pentene Via Catalytic Asymmetric Hydrovinylation". Organic Syntheses. 85: 248–266. doi:10.15227/orgsyn.085.0248. PMC 2723857. PMID 19672483.
  6. ^ Grutters, M. M. P.; Muller, C.; Vogt, D. (2006). "Highly Selective Cobalt-Catalyzed Hydrovinylation of Styrene". J. Am. Chem. Soc. 128 (23): 7414–5. doi:10.1021/ja058095y. PMID 16756275.
  7. ^ Hilt, G.; Danz, M.; Treutwein, J. (2009). "Cobalt-Catalyzed 1,4-Hydrovinylation of Styrenes and 1-Aryl-1,3-butadienes". Org. Lett. 11 (15): 3322–5. doi:10.1021/ol901064p. PMID 19583205.
  8. ^ Sharma, R. K.; RajanBabu, T. V. (2010). "Asymmetric Hydrovinylation of Unactivated Linear 1,3-Dienes". J. Am. Chem. Soc. 132 (10): 3295–7. doi:10.1021/ja1004703. PMC 2836389. PMID 20163120.
  9. ^ Tony C. T. Chang, Myron Rosenblum, Nancy Simms (1988). "Vinylation of Enolates with a Vinyl Cation Equivalent: trans-3-Methyl-2-Vinylcyclohexanone". Organic Syntheses. 66: 95. doi:10.15227/orgsyn.066.0095.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. ^ Murai, Shinji; Kakiuchi, Fumitoshi; Sekine, Shinya; Tanaka, Yasuo; Kamatani, Asayuki; Sonoda, Motohiro; Chatani, Naoto (1993-12-09). "Efficient catalytic addition of aromatic carbon-hydrogen bonds to olefins". Nature. 366 (6455): 529–531. Bibcode:1993Natur.366..529M. doi:10.1038/366529a0. S2CID 5627826.
  11. ^ Jia, C.; Kitamura, T.; Fujiwara, Y. (2001). "Catalytic Functionalization of Arenes and Alkanes Via C-H Bond Activation". Acc. Chem. Res. 34 (8): 633–639. doi:10.1021/ar000209h. PMID 11513570.
  12. ^ Shen, Hong C. (2008). "Recent advances in syntheses of heterocycles and carbocycles via homogeneous gold catalysis. Part 1: Heteroatom addition and hydroarylation reactions of alkynes, allenes, and alkenes". Tetrahedron. 64 (18): 3885–3903. doi:10.1016/j.tet.2008.01.081.
  13. ^ Li, Yuexuan; Deng, Gongda; Zeng, Xiaoming (2016). "Chromium-Catalyzed Regioselective Hydropyridination of Styrenes". Organometallics. 35 (5): 747–750. doi:10.1021/acs.organomet.5b01021.