1.3- Dithietanes with antimony trifluoride

A one-pot synthesis of alkyl perfluoroalkyl ketones has been developed. Phosphoranes, generated in situ, are acylated with a perfluoroacyl anhydnde, and the resultmg phosphonium salts are hydrolyzed with alkali [4S (equation 48) Hydrolysis of a carbon-sulfur bond in 2-chloro-2,4,4-trifluoro-1,3-dithietane-S-trioxide, which can be obtained from 2,2,4,4-tetrachloro-l,3-dithietane by fluor-mation with antimony trifluoride followed by selective oxidations, opens the nng to produce 2-chloro-1,1,2-trifluorodimethyl sulfone [49] (equation 49)... 

A number of routes to thiocarbonyl fluoride that do not involve tetrafluoro-dithietane have been developed. In one (50), phosgene is chlorinated to give tri-chlorosulfenyl chloride, which is converted to chlorodifluorosulfenyi chloride by reaction with antimony trifluoride, and the fluorinated compound is then dehalogenated by reaction with tin. 

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