Sulfones thietane 1,1-dioxides

The smallest four-membered ring sulfone, thietane-1,1-dioxide (94) and the related thiete-1,1-dioxide (95), were studied using PE and electron transmission (ET) spectroscopies by Gleiter and coworkers62. A comparison with the spectra of halogenated derivatives allows unambiguous assignment of the n ionization and the n attachment... 

It appears, however, that the most used strategy for the preparation of thietane dioxides is the [2 + 2] cycloaddition of enamines (202) with in situ-generated sulfenes (220)74,143,186 188,202,242 to give /(-aminothietane sulfones (equation 85). 

The preparation and investigation of the thietane oxide system (5a) is largely associated with stereochemical and conformational studies . The investigation of the thietane dioxides (5b) is substantially related to the chemistry of sulfenes , the [2 -I- 2] cycloaddition of which with enamines is probably the method of choice for the synthesis of 5b . The study of the thiete dioxide system (6) evolved, at least in part, from the recognition that the unstable thiete system 183 can be uniquely stabilized when the sulfur in the system is transformed into the corresponding sulfone , and that the thiete dioxide system is very useful in cycloadditions and thermolytic reactions. The main interest in the dithietane oxides and dioxides (7) appears to lie in the synthetic challenge associated with their preparation, as well as in their unique structural features and chemical behavior under thermolytic conditions . ... 

A variety of examples of photochemically induced elimination of sulfur dioxide from sulfur heterocycles have been reported, with particular attention to cyclic sulfones. Thietan-3-one 1,1-dioxide (525), however, undergoes fragmentation on irradiation in acetonitrile to ketene (526) and to the sulfene (527), the latter identified by infrared spectroscopy and as the methanol... 

The following compounds have been obtained from thiete 1,1-dioxide Substituted cycloheptatrienes, benzyl o-toluenethiosulfinate, pyrazoles, - naphthothiete 1,1-dioxides, and 3-subst1tuted thietane 1,1-dioxides.It is a dienophile in Diels-Alder reactions and undergoes cycloadditions with enamines, dienamines, and ynamines. Thiete 1,1-dioxide is a source of the novel intermediate, vinylsulfene (CH2=CHCH=SQ2). which undergoes cyclo-additions to strained olefinic double bonds, reacts with phenol to give allyl sulfonate derivatives or cyclizes unimolecularly to give an unsaturated sultene. - Platinum and iron complexes of thiete 1,1-dioxide have been reported. 

Carbon-13 chemical shifts of the a- and (8-carbon atoms of various unsubstituted and 3-substituted thietane oxides and dioxides have been recorded and correlated by the equations S = ay + bx and Sf = ax + by where a and b are parameters characteristic of the sulfoxide or sulfone (y) and the substituent (x)216. The values of the substituent parameters were found to parallel those which determine the effect on the 13C chemical shifts when hydrogen is replaced by a substituent224. 

A few studies have been carried out on the parent four- and five-membered cyclic sulfones—for thietane 1,1-dioxide (30) by Scala and Colon65 and for thiolane 1,1-dioxide (sulfolane) (31) by Honda and coworkers66 and, later, by Schuchmann and von Sonntag67. In the former compound, the major photochemical process, in the vacuum UV range, is the initial production of a trimethylene (C3H6) biradical and S02 (equation 9). In both the solid- (77 K) and gas-phase photolyses, formation of a triplet biradical appears to be favored. As well as the expected cyclopropane and propylene, ethylene is also obtained during these photolyses, presumably by a cycloreversion process (equation 10). 

A preparation of 3-substituted thiete dioxides takes advantage of the commercial availability of the parent four-membered thietanes. The latter is oxidized to the sulfone, which in turn is photochemically mono- or di-chlorinated in the 3-position. The 3-chlorothietane dioxide (239a) can be easily transformed into the thiete dioxide, whereas the 3,3-dichloro homolog is transformed into the 3-chloro-2H-thiete 1,1-dioxide (240b) (equation 91). 240b reacts with carbanions, amines, alcohols and thiols to give the corresponding 3-substituted thiete dioxides. ... 

The reaction of Af,Af-dimethyl-( )-styrylamine (73) with a halogen-substituted methanesulfonyl chloride allowed the first stereoselective formation of the halogenated thietane 1,1-dioxide 74, which then could be converted to the corresponding thiete sulfone 75 via a Cope elimination of the corresponding AT-oxide. ... 

Free radical bromination of thietane 1,1-dioxide takes place at the 3- rather than the 2-position, giving ultimately 3,3-dibromothietane 1,1-dioxide (80) (76JOC3044). This preference for abstraction of a hydrogen atom /3 to a sulfonyl group reflects the instability of a free radical a to a sulfone function. 

Conversion of thietane 1-oxides and 1,1-dioxides back to thietanes can be accomplished with aqueous sodium bisulfite (limited to thietane 1-oxides (72JOC919)) or more generally with LAH, as illustrated for sulfoxide (189) (79JOC4757) and sulfone (190) <65LA(684)92, 69JA2796). Ring-substituted thietanes are often conveniently prepared by ring functionalization of the thietane 1,1-dioxide followed by LAH reduction, as will be illustrated below. 

The isolation of thiirane oxides prepared by oxidation of the corresponding thiiranes is problematic, and the isolation of thiirane dioxides from the direct oxidation of thiiranes or thiirane oxides has yet to be reported. However, highly strained fused-ring thiiranes can be successfully oxidized to thiirane oxides (e.g. 41) with MCPBA or NaI04 under carefully controlled conditions (82CB3213). Thietane can be oxidized to a sulfone. 

A limited amount of 170 NMR chemical shift data is available for thietane 1-oxides and 1,1-dioxides and thiete 1,1-dioxides. These data, summarized along with selected data for rings of other sizes in Table 4, indicate that there is once again a maximum in deshielding at the four-membered ring. As can also be seen, discrete nO NMR chemical shifts are observed for the nonequivalent sulfone oxygens in several of the thietane 1,1-dioxides. 

Treatment of 3-hydroxythietanes 21b-g with aqueous sodium hydroxide led to retro-aldol ring cleavage to produce the carbonyl derivatives 23b-g (Table 1) <1997J(P2)425>. It was proven that the rate of the reaction was determined by the nature of the substituent at the 3-position and by the oxidation state of sulfur. 3-Phenylthietane-3-ol 21b underwent retro-aldol reaction to give sulfide ketone 23b. Thietane-l-oxide-3-ol 21c-e or thietane-l,l-dioxide-3-ol 2 If and 21g derivatives underwent retro-aldol reaction to produce carbonyl sulfoxides 23c-e and carbonyl sulfones 23f and 23g (Table 1) <1997J(P2)425>. 

Sulfenes (RCH=S02) (usually generated in situ from the corresponding sulfonyl chlorides in the presence of triethylamine) react with enamines to give [2 + 2] cycloadducts (thietane 1,1-dioxides)106-110 or open-chain sulfones depending on the nature of R in RCH2S02C1. Generally, cyclization occurs when R = H or Ar but not when R = Alkyl. The putative mechanism of this cyclization involves a two-step process via a zwitterionic intermediate 200 (equation 43)108. 

Thietanes may be converted to 5-oxides or 5,5-dioxides (sulfoxides and sulfones, respectively) by treatment with oxidizing agents. Hydrogen peroxide (30%) is most commonly used usually in acetic... 

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