Fluoromethyl Phenyl Sulfone1

[20808-12-2]  · C7H7FO2S  · Fluoromethyl Phenyl Sulfone  · (MW 174.21)

(synthesis of a-fluoro-a,b-unsaturated sulfones,1b,d,2 vinyl fluorides1b,d,2)

Physical Data: mp 50-51 °C (from MeOH).

Solubility: sol THF, CHCl3, CH2Cl2.

Preparative Method: by the oxidation of Fluoromethyl Phenyl Sulfide with two equivalents of m-Chloroperbenzoic Acid (eq 1).1b,c

a-Fluoro-a,b-Unsaturated Sulfones and Vinyl Fluorides.

The reaction of phenylsulfonylfluoromethyllithium, generated by the reaction of fluoromethyl phenyl sulfone with n-Butyllithium, with carbonyl compounds gives the a-fluoro-b-hydroxyphenylsulfonyl derivatives in good yields; upon dehydration with Methanesulfonyl Chloride, these give the corresponding vinyl sulfones. Reductive desulfonylation with Aluminum Amalgam yields vinyl fluorides (eq 2).1b The overall process represents the use of fluoromethyl phenyl sulfone as a fluoromethyl Wittig equivalent. This method of preparation of vinyl fluorides is complementary to the existing few methods, e.g. the use of Fluoromethylenetriphenylphosphorane3 and Fluoromethyl Phenyl Sulfoxide.4

The Wittig-type reaction of the diethyl 1-fluoro-1-(phenylsulfonyl)methanephosphonate carbanion, generated in situ from fluoromethyl phenyl sulfone with diethyl chlorophosphate and two equivalents of either Lithium Diisopropylamide or Lithium Hexamethyldisilazide at -78 °C, with carbonyl compounds gives a-fluoro-a,b-unsaturated sulfones in good to excellent yields (eq 3).1d

A similar Wittig reaction of 1-fluoro-1-(phenylsulfonyl)methanephosphonate carbanion is used in the synthesis of 2-deoxy-2-fluoromethylene nucleosides (eq 4).2

Diethyl 1-fluoro-1-phenylsulfonylmethanephosphonate can also be prepared by the direct fluorination of diethyl (phenylsulfonyl)methanephosphonate with Perchloryl Fluoride (FClO3) (eq 5).5 The Wittig reagent derived from it is used in the preparation of a number of alkylated a-fluorophenylsulfonyl derivatives and a-fluoro-a,b-unsaturated sulfones (eqs 6 and 7).5 1-Fluoro-1-(phenylsulfonyl)ethylene can also be prepared by the elimination of 2-chloro-1-fluoroethyl phenyl sulfone (eq 8).6 Diels-Alder cycloadditions, Michael reactions (eq 9),5 1,3-dipolar cycloaddition (eq 10),7 and radical addition (eq 10)6 reactions of 1-fluoro-1-(phenylsulfonyl)ethylene have been demonstrated.

1. (a) Schlosser, M. T 1978, 34, 3. (b) Inbasekaran, M.; Peet, N. P.; McCarthy, J. R.; LeTourneau, M. E. CC 1985, 678. (c) McCarthy, J. R.; Peet, N. P.; LeTourneau, M. E.; Inbasekaran, M. JACS 1985, 107, 735. (d) McCarthy, J. R.; Matthews, D. P.; Edwards, M. L.; Stemerick, D. M.; Jarvi, E. T. TL 1990, 31, 5449. (e) Robins, M. J.; Wnuk, S. F. JOC 1993, 58, 3800.
2. (a) Simpkins, N. S. T 1990, 46, 6951. (b) McCarthy, J. R.; Matthews, D. P.; Stemerick, D. M.; Huber, E. W.; Bey, P.; Lippert, B. J.; Snyder, R. D.; Sunkara, P. S. JACS 1991, 113, 7439.
3. (a) Burton, D. J.; Greenlimb, P. E. JOC 1975, 40, 2796. (b) Bey, P.; Fozard, J.; Lacoste, J. M.; McDonald, I. A.; Zreika, M.; Palfreyman, M. G. JMC 1984, 27, 9. (c) McDonald, I. A.; Lacoste, J. M.; Bey, P.; Wagner, J.; Zreika, M.; Palfreyman, M. G. JACS 1984, 106, 3354. (d) Takeuchi, Y.; Nagata, K.; Koizumi, T. JOC 1989, 54, 5453.
4. Reutrakul, V.; Rukachaisirikul, V. TL 1983, 24, 725.
5. Koizumi, T.; Hugi, T.; Horie, Y.; Takeuchi, Y. CPB 1987, 35, 3959.
6. Matthews, D. P.; McCarthy, J. R. JOC 1990, 55, 2973.
7. Takahashi, T.; Hagi, T., Kitano, K.; Takeuchi, Y.; Koizumi, T. CL 1989, 593.

Vichai Reutrakul & Manat Pohmakotr

Mahidol University, Bangkok, Thailand

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