Pummerer rearrangement
The Pummerer rearrangement is a chemical reaction whereby an alkyl sulfoxide rearranges to an α-acyloxythioether in the presence of acetic anhydride.[1][2] In this reaction, sulfur is reduced while adjacent carbon is oxidized.
Several reviews have been published.[3][4][5]
The usage of α-acyl sulfoxides and Lewis acids, such as TiCl4 and SnCl4, allow the reaction to proceed at lower temperatures (0 °C).[6]
Mechanism
The mechanism of the Pummerer rearrangement begins with the acylation of the sulfoxide (1 and 2). Compound 3 undergoes elimation to produce the sulfonium ion 4. Acetate adds to the sulfonium ion to give the final product 5.
Other anhydrides and acyl halides can give similar products. Inorganic acids can also give this reaction.This product can be converted to aldehyde or ketone by hydrolysis.[7]
Variations
The sulfonium ion can be trapped by both intramolecular and intermolecular nucleophiles forming carbon-carbon bonds and carbon-heteroatom bonds. For example, thionyl chloride can be used to generate and trap the sulfonium ion:[8]
Likewise, nucleophiles (such as veratrole[9]) can also be used.
References
- ^ Pummerer, R. Ber. 1909, 42, 2282.
- ^ Pummerer, R. Ber. 1910, 43, 1401.
- ^ De Lucchi, O.; Miotti, U.; Modena, G. Org. React. 1991, 40, 157-184. (Review)
- ^ Padwa, A.; Gunn, D. E., Jr.; Osterhout, M. H. Synthesis 1997, 1353-1377. (Review)
- ^ Padwa, A.; Rur, S. K.; Danca, M. d.; Ginn, J. D.; Lynch, S. M. Synlett 2002, 851-862. (Review)
- ^ Stamos, I. K. Tetrahedron Lett. 1986, 27, 6261.
- ^ Meffre, P.; Durand, P.; Le Goffic, F. Organic Syntheses, Coll. Vol. 10, p.562 (2004); Vol. 76, p.123 (1999). (Article)
- ^ Kosugi, H.; Watanabe, Y.; Uda, H. Chem. Lett. 1989, 1865.
- ^ Ishibashi, H. et al. Chem. Pharm. Bull. 1989, 37, 3396.