[20808-12-2] · C7H7FO2S · Fluoromethyl Phenyl Sulfone · (MW 174.21)
Physical Data: mp 50-51 °C (from MeOH).
Solubility: sol THF, CHCl3, CH2Cl2.
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.
Vichai Reutrakul & Manat Pohmakotr
Mahidol University, Bangkok, Thailand