Synthesis of new synthons for organofluorine compounds from halothane containing sulfur functional groups

To develop new synthons for the syntheses of organofluorine compounds, the treatment of Halothane, 2-bromo-2-chloro-1,1,1-trifluoroethane, (1) with 4- methylbenzenethiol (2) in the presence of sodium hydride gave 1-chloro-2,2, 2-trifluoroethyl 4-methylphenyl sulfide (3), which was oxidized with m-chlo roperbenzoic acid (m-CPBA) to the corresponding sulfoxide (4) and sulfone ( 5), Reaction of 3 and 5 with allyltributyltin in the presence of 2,2'-azobi s(isobutyronitrile) (AIBN) gave 1-(trifluoromethyl)-3-butenyl compounds (9, 11), Sulfoxide 4 was decomposed in this condition. The treatment of 3 with allyltrimethylsilane in the presence of Lewis acids gave 1-(trifluoromethy l)-3-butenyl compounds (9) in good yield. This result suggests that 4-methy lphenylthio substituent stabilizes the alpha-arbocation effectively, though the trifluoromethyl group destabilizes it strongly. Aromatic compounds sim ilarly reacted with 3 in the presence of titanium(IV) chloride to give 2-ar yl-1,1,1-trifluoro-2-(4-methylphenylthio)ethanes. Thus, sulfur compounds de rived from Halothane were found to be useful new synthons for organofluorin e compounds.