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Barton–Kellogg reaction

Lianyungang Klinechem Co.,Ltd | Updated: Nov 29, 2018

The Barton–Kellogg reaction is a coupling reaction between a diazo compound and a thioketone through an episulfide intermediate forming an alkene.[1][2][3] The Barton–Kellogg reaction is also known as Barton–Kellogg olefination[4] and Barton olefin synthesis.[5]

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This reaction was pioneered by Hermann Staudinger,[6] and the reaction also goes by the name Staudinger type diazo-thioketone coupling.

Reaction mechanism

In the reaction mechanism for this reaction the diazo compound is a 1,3-dipole which reacts with the thioketone in a 1,3-dipolar cycloaddition to a thiadiazoline. This intermediate is unstable and through nitrogen gas expulsion and formation of an intermediate thiocarbonyl ylide it forms a stable episulfideTriphenylphosphine opens the three-membered ring and then forms a sulfaphosphatane in a manner similar to the Wittig reaction. In the final step triphenylphosphine sulfide is expulsed liberating the alkene.

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Scope

The diazo compound can be obtained from a ketone by reaction with hydrazine to a hydrazone followed by oxidation. Many reagents exist for this conversion for example silver(I) oxide and (bis(trifluoroacetoxy)iodo)benzene.[7] The thioketonerequired for this reaction can be obtained from a ketone and phosphorus pentasulfide. Desulfurization of the episulfide can be accomplished by many phosphines and also by copper powder.

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The main advantage of this reaction over the McMurry reaction is the notion that the reaction can take place with two different ketones. In this regard the diazo-thioketone coupling is a cross-coupling rather than a homocoupling.

References

1.   ^ D. H. R. Barton & B. J. Willis (1970). "Olefin synthesis by twofold extrusion processes". J. Chem. Soc. D (19): 1225. doi:10.1039/C29700001225.

2.   ^ R. M. Kellogg & S. Wassenaar (1970). "Thiocarbonyl ylides. An approach to "tetravalent sulfur" compounds". Tetrahedron Lett. 11 (23): 1987. doi:10.1016/S0040-4039(01)98134-1.

3.   ^ R. M. Kellogg (1976). "The molecules R2CXCR2 including azomethine, carbonyl and thiocarbonyl ylides. Their syntheses, properties and reactions". Tetrahedron32 (18): 2165. doi:10.1016/0040-4020(76)85131-9.

4.   ^ "Barton-Kellogg olefination". Comprehensive Organic Name Reactions and Reagents. 2010. pp. 249–253. doi:10.1002/9780470638859.conrr056.

5.   ^ "Barton olefin synthesis"Merck Index (15th ed.).

6.   ^ H. Staudinger & J. Siegwart (1920). "Einwirkungen von aliphatischen Diazoverbindungen auf Thioketone". Helv. Chim. Acta3: 833. doi:10.1002/hlca.19200030178.

7.   ^ Matthijs K. J. ter Wiel; Javier Vicario; Stephen G. Davey; Auke Meetsma & Ben L. Feringa (2005). "New procedure for the preparation of highly sterically hindered alkenes using a hypervalent iodine reagent". Organic & Biomolecular Chemistry3: 28–30. doi:10.1039/b414959a.


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