Thiete 1,1-dioxides thermolysis

The photolysis of various substituted thiete dioxides under similar conditions resulted in the formation of the unsaturated ketones (255)264, most probably via a vinyl sulfene intermediate followed by a loss of sulfur monoxide as shown in equation 96. The same results were obtained in the thermolysis of 6e (R1 = R3 = Ph R2 = R4 = H)231, which further demonstrates that similar mechanisms are operative in thermolyses and pho-tolyses of thietane dioxides and thiete dioxides. 

The formation of cyclic sulfinic esters (sultines) from vinyl sulfenes is known , and the trapping of the expected intermediate vinyl sulfene in the thermolysis of thiete dioxide (6fc and 194) has been convincingly achieved . Specifically, thermolysis of thiete dioxide 6b in the presence of norbornenes gave cycloadducts of the Diels-Alder type (i.e. 252b), resulting from the trapping of the vinyl sulfene formed. The accumulated evidence thus supports the proposed mechanism for these thermolytic reactions. 

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... 

Mass spectrometry was applied in conjunction with thermolysis studies leading mainly to sulfines and rearranged products with four-membered sulfoxides and to a loss of sulfur dioxide with sulfones The fragmentation pattern of thietes under electron impact can be explained by the sequential loss of the elements of sulfur monoxide and oxygen from an intervening cyclic sulfmate intermediate . ... 

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. 

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. ... 

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). 

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... 

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... 

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 =... 

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. ... 

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... 

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