Thietane sulfuranes

Thietane sulfuranes and one persulfurane have been mentioned previously in Section II.5.D. The sulfurane 86 and persulfurane 87 are obtained from thietane and 3-methylthietane by treatment with trifluoromethyl hypofluorite. The sulfurane 86 (R = H) ionizes to the 1-fluorothietanium ion 194. Diiodosulfuranes have been reported/ but the dibromo derivatives are unstable. These sulfuranes may be hydrolyzed to sulfoxides (Section III.3.B.). 

The rate was retarded by added chloride ion (common-ion effect) but no 3-chloro-thietane was identified among the products. No reaction occurred in the absence of acetate. The possible intermediacy of a sulfurane, proposed in reactions of epi-sulfonium salts/ was not considered. 

Treatment of thietane with chlorine, bromine,or sulfuryl chloride yields ring-opened materials. Trifluoromethyl hypofluorite gives tetravalent and hexa-valent sulfur-fluorine compounds 86 (a sulfurane) and 87 (a persulfurane) from thietane and 3-methylthietane. Ionization of 86 (R = H) at —20° to — 40°C was indicated by the collapse of the two doublets observed in the F nmr spec-... 

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