1.2- Oxathietane 2,2-dioxides

Acid-catalyzed rearrangement of 1,1 -diphenyl-2,2-dimethylpropanol in presence of sulfur trioxide forms a stable 1,2-oxathietane 2,2-dioxide (Scheme 18) (77JCS(P1)247). 

The synthesis of the 4,5-dimethoxy-l,3,2-dioxathiolane 2,2-dioxide (98) from perfluoro-2-butene involved reaction with sodium methoxide, resulting in a mixture of cis and trans isomers of the vinyl diether (197). Subsequent action of sulfur trioxide on (197) gave, probably via the 1,2-oxathietane 2,2-dioxide (198), the cyclic sulfate (98) (77JA1214), a convenient precursor to hexafluorobiacetyl (c/. Section 4.33.3.3.1). 

IZV118) and the formation of (31) is analogous to the reaction (197)->(98) via a four-membered 1,2-oxathietane 2,2-dioxide intermediate. Subsequent products derived from (31) by electrophilic addition reactions at the alkenic double bond have been described in Section 4.33.3.2.2 and the synthesis of 4,5-dichloro-l,3,2-dioxathiolane 2,2-dioxide (154) by chlorination of ethylene sulfate (18) is discussed in Section 4.33.3.5. Cyclic sulfites, on the other hand, cannot be halogenated without ring opening (cfSection 4.33.3.2.4). 

Oxathietane 2,2-dioxides (-sultones) are prepared by [2 + 2] cycloaddition of sulfur trioxide to alkenes (e.g., Scheme 27) . Likewise, acid-catalyzed rearrangement of l,l-diphenyl-2,2-dimethylpropanol in the presence of sulfur trioxide forms a stable 1,2-oxathietane 2,2-dioxide (Scheme 28) < 1977J (Pl)247>. 

XXX. 1,2-OXATHIETANES 1,2-OXATHIETANE 2-OXIDES (jS-SULTINES) 1,2-OXATHIETANE 2,2-DIOXIDES (j3-SULTONES)... 

Oxathietane 2,2-dioxides are claimed to be useful in the synthesis of pharmaceuticals diseases, ... 

The S-0 stretching frequency in the IR spectra of 1,2-oxathietane 2-oxides is observed at 1150-1190cm . The carbonyl stretching frequency in 1,2-oxathietane-4-one 2-oxide is observed at 1840 and 1856 cm". The sulfonate IR absorptions in 1,2-oxathietane 2,2-dioxides are 1370-1408 and 1176-1235 cm", except for the fluorinated derivatives, the absorption of the tetrafluoro- 3-sultone being reported at 1470cm". Fluorine-19 (nmr) chemical shifts and coupling constants are useful in structural and conformational studies of... 

Oxathietane 2,2-dioxides (e.g., 448) are isolated in good yields from the reaction of sulfur trioxide with fluorinated alkenes, fluorinated dienes, ° and from the reaction of the sulfur trioxide donor 499 with fluorinated alkenes. Zwitterionic intermediates ( C-C-S020 ) are suggested. An explosion has been reported in the addition of sulfur trioxide to tetrafluoro-ethylene. Tetrafluoroethane /3-sultone (498) also is obtained by treatment of fluorosulfonyldifluoroacetic anhydride with antimony trichloride. ... 

Several j3-sultones are claimed to be formed by treatment of alkenes with sulfuric acid or by heating alkenesulfonic acids. Treatment of 2,2-dimethyl-1,1-diphenyl-1-propanol with concentrated sulfuric acid at room temperature is said to give 3-(l,l-diphenylethyl)-3-methyl-l,2-oxathietane 2,2-dioxide (96% yield). Treatment of sodium 3-bromo-2-hydroxybutanesulfonate with phosphorus trichloride is reported to give a low yield of 4-(l-bromoethyl)-l,2-oxathietane 2,2-dioxide.1,2-Oxathietane 2,2-dioxide is suggested as an intermediate in the reaction of /3-hydroxyethanesulfonyl chloride with trimethylamine to give the zwitterion 502. The first four-membered monocycUc sulfurane oxides 502a have been reported. 

The IR of 1,2-oxathietane dioxide shows an asymmetric S02 stretch at 1394 and a symmetric one at 1176 cm 1 (67DOK(172)1327). The corresponding monoxides appear at 1150 cm"1 (75CC724). The chemical shifts and coupling constants have been used to assign the cis and trans structures to 3,4-dimethyl-1,2-oxathietane dioxide (73CC841). 

The thermolysis of fluorinated /3-sultones, the most stable derivatives of oxathietane dioxides, generally gives isomerization rather than elimination (Scheme 18) (72AG(E)583). 

Perfluorinated 1,2-oxathietane dioxides, /3-sultones, are the most stable derivatives and, as such, the most widely studied. They undergo some of the more unique reactions, especially those with acid halides which are regarded mechanistically as a concerted displacement (Scheme 53) (67BAU1935). 

Technological applications have been found for the oxathietane 1,1-dioxides. Ethane ) -sultones (19) substituted with long, saturated hydrocarbon chains have been developed as foam-producing surfactants and detergents. Attention is being given to the fluorinated sultones (20), especially by Soviet... 

The thermal decomposition of 1,2-oxathietane 2-oxides invariably leads to loss of sulfur dioxide and accompanying alkene formation (Scheme 17) (73JA3420, 78BAU142). The lack of any solvent polarity effect on rate (75CC724) as well as supporting theoretical calculations favor a concerted loss of sulfur dioxide without requiring a strained [[Pg.459]

The intermediacy of a 4-imino- 1,2-oxathietane 2-oxide from the addition of sulfur dioxide to ketenimines was inferred from the trapping with methanol. The final isolated product in absence of methanol, l,2-thiazetidin-3-one 1-oxide, was established by X-ray (Scheme 42) (81CC350). 

Several examples of polyhalogenated alkene addition to sulfur dioxide (60JA6181, 66JCS(C)ll7i> are known to give moderately stable 1,2-oxathietane 2-oxide adducts (Scheme 99) (78BAU142, 79BAU106). 

Ketene is reported to add photochemically in an argon matrix to sulfur dioxide giving l,2-oxathietan-4-one 2-oxide (75CC724). 

The 15CH coupling constants (often obtained from 13C satellites in H NMR spectra) of small heterocycles have been listed <1979MI50101>. A 13C NMR study of 1,2-dimcthyl-3-/W/-butyldiaziridinc showed that the population of the 1,2-cis isomer increases with solvent polarity (see Section 2.5.3.8) <1998MC113>. 13C Chemical shifts for the ring carbons of representative derivatives of dithiiranes , azetidines , diazetidines , thiazetidines , dioxetanes , and 1,2-oxathietane S,A-dioxides (-sultones) have been tabulated. 

Trifluoro-3-(fluorosulfonyl)-l,2-oxathietane 2,2-Dioxide (4) Single Procedure ... 

Oxathietan 3-Methyl-4-trichlor-methyl- -2,2-dioxid Ell, 1581 (Cl3C-CHO + H5C2-S02-C1)... 

Several 3-substituted 4-trichloromcthyl-l,2-oxathietane 2,2-oxides 9 with irons configuration have been prepared by cycloaddition of thialdehyde S, 5-dioxides to chloral119. 

A reaction closely related to the [2 + 2] cycloaddition of thiocarbonyl S.S-dioxides is the addition of sulfur trioxide-dioxane complex to alkenes. This occurs stereoselectively and from (Z)- and (E)-2-butene the corresponding cis- and /ra .s -3,4-dimethyl-1,2-oxathietane 1,1-dioxides 11 are obtained121. 

Oxathietanes are rare, having been suggested as intermediates in a few instances but not one has yet been isolated. The 5-dioxides or j3-sultines are more... 

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