Thermolysis of Thiet 1,1-Dioxides

Thermolysis of thiete 1,1-dioxide (116), either in the vapor phase or in benzene solution, gives the oxathiole (117) in over 80% yield. The most likely mechanism involves a sulfene intermediate as shown in Scheme 38 (70CJC3704). Not surprisingly, the flash thermolysis of thietane 1,1-dioxide, the saturated analog of (116), gives only cyclopropane and propene. 

Vinylsulfenes (115), generated by thermolysis of thiete-1,1-dioxides (116), react with the strained cycloalkene norbornene (117) to give [4 + 2] cycloadducts (118) (Scheme 74). 

Electrophilic sulfenes, R2CMSO2, are recognized for their ability to react with nucleophiles and for their 2ir participation in [2 + 2] and [4 + 2] cycloadditions (Chapter 5). Less well recognized is the demonstrated 4ir participation of vinyl sulfenes in Diels-Alder reactions with a select set of dienophiles. Thermolysis of thiete 1,1-dioxides including the parent thiete 1,1-dioxide (22) in the presence of norbornenes provided the Diels-Alder products derived from 4w participation of the vinyl sulfenes [Eq. (18)].40... 

Dittmer and coworkers119 generated vinylsulfenes by thermolysis of thiete 1,1-dioxides which, in the presence of norbornenes, gave the Diels-Alder-type cycloadducts 124 in good yield (equation 111) (see also Section IV.E.2). Thermolysis of thiete 1,1-dioxide in... 

Thermolysis of thiete 1,1-dioxide 34 in the presence of norbornene affords the [4+2] cycloadduct 36 of the generated vinyl sulfene 35 to the olefin. ... 

Electrolysis of benzothiete sulfone 269 yields the phenylmethanesulfinate anion (major) and the o-toluenesulfinate anion (minor).Thermolysis 618,619 gj. photolysis of thiete 1,1-dioxides proceeds via ring-opening to vinyl sulfines, for example. 288, which have been trapped by reaction with water, phenol,methanol, or norbornenes. These intermediates may recyclize to unsaturated sultines (cyclic sulfinate esters) (e.g., 289) or lose sulfur monoxide to give mainly the trans isomers of a,j3-unsaturated carbonyl compounds (e.g., 290). Mass spectra also indicate the formation of unsaturated sultines. ... 

The dienophilicity of thiet 1,1-dioxide was utilized to synthesize (73) from tetracyclone, whilst it acted also as a good dipolarophile towards diazoalkanes, giving mixtures of 1-pyrazoline derivatives (74) and (75) in which the isomers (74) predominated, except in the cases of diazomethane and diazoethane, where (75) was the major isomer. Ethyl diazoacetate on the other hand gave the 2-pyrazoline (76). These compounds arc potentially useful for the synthesis of bicyclobutanes by sequential expulsion of nitrogen and sulphur, and thermolysis or photol3rsis of (74 = R =... 

Oxygen and Sulphur-containing Heterocycles.—Dittmer and Nelsen have improved the yield of the known benzo[/>]thiete-1,1-dioxide (281) which was prepared in six steps from (280) thermolysis of (281) gave the sultine (282). Improved... 

Thermolysis of Thiet Dioxides, In the vapour phase at 400 °C or in solution at 220 °C, thiet 1,1-dioxide (80) gave the cyclic sulphinate (81), the intermediate vinylsulphene in this rearrangement (Scheme 12) being... 

Gas-phase thermolysis of thietane S-oxide at 500-1130°C and lO Torr provides one method for generation of 1,2-oxathiolane (5) <81JCS(P2)1I66>. As described in the first edition, thermal ring expansion of thiete 1,1-dioxide provides the most convenient access to 1,2-oxathiole 2-oxide (7) and this reaction has also been used to obtain the 3-phenyl- <72TL4781>, 3,5-diphenyl- <77JOC3506>, and... 

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