Dimethyl Sulfone

[67-71-0]  · C2H6O2S  · Dimethyl Sulfone  · (MW 94.15)

((methanesulfonyl)methylation agent; may be used as a dipolar aprotic solvent)

Physical Data: mp 108-110 °C; bp 238 °C; d 1.1707 g cm-3 (110 °C); pKa 31.1 (DMSO) and 23 (water).

Solubility: sol in hot H2O, EtOH, benzene.

Form Supplied in: white solid; commercially available.

Purification: recrystallized from CHCl3 or H2O and then dried over P2O5.

Handling, Storage, and Precautions: stable indefinitely at rt.

As a Solvent.

Because of its high boiling point, dimethyl sulfone is a convenient solvent for high-temperature reactions, e.g. treatment of 2-chloropyridine with Potassium Fluoride in dimethyl sulfone at 110 °C for 21 days results in the displacement of the chlorine by fluorine.1

Reactivity and Applications.

Dimethyl sulfone can be deprotonated by organolithium compounds, Grignard reagents, or alkali metal alkoxides,2 amides,3,4 or hydrides5 to give (methanesulfonyl)methyllithium or (methanesulfonyl)methyldilithium, depending upon the amount of base added.3 The choice of the solvent (THF, DMSO, or liquid ammonia) is dictated by the nature of the base. The resultant carbanions react with halides, aldehydes,4 ketones, esters, nitriles,3 or amides. Under phase transfer catalysis, condensation of dimethyl sulfone with aldehydes occurs without dehydration to give the corresponding b-hydroxysulfones.6 The acidity of dimethyl sulfone (pKa = 31) is greatly enhanced by forming Trifluoromethanesulfonylmethyl Methyl Sulfone (pKa = 4) via reaction of (methanesulfonyl)methylmagnesium bromide with trifluoromethanesulfonyl fluoride or Trifluoromethanesulfonic Anhydride. The trifluoromethanesulfonyl group serves the dual role of acidity enhancer and leaving group in a Ramberg-Bäcklund reaction, leading to a synthesis of alkenes.7 The principles are illustrated in a synthesis of the cyclopentenone ring of dihydrojasmone (eq 1).8

Related Reagents.

Methyl Phenyl Sulfone; Trifluoromethanesulfonylmethyl Methyl Sulfone.

1. Finger, G. C.; Starr, L. D.; Dickerson, D. R.; Gutowsky, H. S.; Hamer, J. JOC 1963, 28, 1666.
2. Becker, H.-D.; Russell, G. A. JOC 1963, 28, 1896.
3. Kaiser, E. M.; Beard, R. D.; Hauser, C. R. JOM 1973, 59, 53.
4. Gokel, G. W.; Gerdes, H. M.; Rebert, N. W. TL 1976, 653.
5. Yokoyama, M.; Tsuji, K.; Hayashi, M.; Imamoto, T. JCS(P1) 1984, 85.
6. Villemin, D.; Richard, M. TL 1984, 25, 1059.
7. Hendrickson, J. B.; Boudreaux, G. J.; Palumbo, P. S. TL 1984, 25, 4617.
8. Hendrickson, J. B.; Palumbo, P. S. JOC 1985, 50, 2110.

Georges Hareau & Philip Kocienski

Southampton University, UK

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