Synthesis of New Synthons for Organofluorine Compounds from Halothane Containing Sulfur Functional Groups

Abstract

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 presnce of sodium hydride gave 1-chloro-2, 2, 2-trifluoroethyl 4-methylphenyl sulfide (3), which was oxidized with m-chloroperbenzoic acid (m-CPBA) to the corresponding sulfoxide (4) and sulfone (5). Reaction of 3 and 5 with allyltributyltin in the presence of 2, 2'-azobis(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-(trifluoromethyl)-3-butenyl compounds (9) in good yield. This result suggests taht 4-methylphenylthio substituent stabilizes the α-carbocation effectively, though the trifluoromethyl group destabilizes it strongly. Aromatic compounds similarly reacted with 3 in the presence of titanium(IV) chloride to give 2-aryl-1, 1, 1-trifluoro-2-(4-methylphenylthio)ethanes. Thus, sulfur compounds derived from Halothane were found to be useful new synthons for organofluorine compounds.