2H-Thiete

THIETE 1,1-OIOXIDE AND 3-CHLOROTHIETE 1,1-DIOXIDE (2H-Thi ete l,l-d1oxi[Pg.210]

C3H402S, 2H-Thiete 1,1-dioxide C4H602S, 2,5-Dihydrothiophene 1,1-dioxide C4H602S, 2,3-Dihydrothiophene 1,1-dioxide CsHgOjS, 2,5-Dihydro-2-methylthiophene 1,1-dioxide C5H802S, 2,5-Dihydro-3-methylthiophene 1,1-dioxide... 

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. ... 

Cycloaddition of CS2 to Fe(C=CMeXdppe)(i/-C5H5) affords the a-2H-thiete-2-thione complex (12), which reacts with iodomethane to give 13, which contains perhaps the most strongly electron-withdrawing ligand known (29) ... 

Some aspects of thiete chemistry have been reviewed. Thiacyclobutene is properly named 2H-thiete, but the designation of hydrogen as a substituent will be omitted in the following discussion. 

An attempted synthesis of thiete by thermolysis (300°) of a Diels-Alder adduct with anthracene was unsuccessful, no doubt because of the thermal instability of thiete.Thiete derivative 215 was obtained by other methods, and structure 217 was suggested as an intermediate in the desulfurization of 216. The unusual dithiolactone 218b is formally derived from a cycloaddition of carbon disulfide with acetylene 218a. " A 2-substituted-3,4-diphenyl-2H-thiete is obtained by treatment of the ylide, 8-methyl-1,3-diphenyldibenzo [e, h]-8-thiazulene, with diphenylcyclo-propenethione. 2-Methoxy-3,4-diphenyl-2H-thiete is one of several products obtained on photolysis of diphenylcyclopropenethione in methanol. ... 

Thiete structures have been suggested as fragmentation products in the mass spectra of a thietane fused to a 3-lactam, an ortho disulfide of a thiolbenzoate ester, -propanethiol, thiirane carboxylic acid esters, isothiazoles, thiazoles, 1,3-dithiole 2-thiones, 1,3-dithiolene-2-ones, S-ethyl thio-benzoate, and thianaphthene sulfones. Tetramethylthiete may have been formed on thermolysis of the p-toluenesulfonyl-hydrazone of 2,2,4,4-tetramethyl-3-thietanone. " Thiete 2-thione may be an intermediate in the decomposition of 1,2-ditholium salts by the action of bases. " 2,2-Diphenyl-2H-thiete is suggested as an intermediate in the reaction of diphenyldiazomethane with 1,2,3-benzo-thiadiazole which yields 9-phenylthioxanthene and three other products. ... 

Treatment of diethyl ketals of 3-thietanone 1,1-dioxide with bases (NaOH, phenyllithium" ) results in the elimination of ethanol to give 3-ethoxythiete 1,1-dioxides, for example, 257. 3-Methoxy-2H-thiete 1,1-dioxide is obtained by elimination of methoxytrimethylsilane from the ketal of 2-trimethylsilyl-3-thietanone 1,1-dioxide. The cycloaddition of ketene yy.,4i7,494b.495a,s93,6oo. 49sa,60i sulfenes derived from... 

Two exomethylene derivatives, 264 and 266, of thiete 1,1-dioxide and three 268a-c of a naphthothiete 1,1-dioxide have been reported. The simplest derivative, 2-methylene-2H-thiete 1,1-dioxide, has not been made. ... 

Additions of the Michael type of nucleophiles to the carbon-carbon double bond of thiete 1,1-dioxides to give 3-substituted thietane 1,1-dioxides occur readily. The addition of hydrogen has been discussed in Section A. Nucleophiles include cyanide, the anion of nitroethane, the lithium salt of r-butyl o-tolyl sulfone, dimethylamine, cyclohexylamine, ethoxide, and hydrogen sulfide. The reaction is exemplified by the synthesis of 278. Additions to 3-chloro-2H-thiete 1,1-dioxide most likely proceed by an addition-elimination mechanism an example is shown for the addition of the anion of dimethylmalonate to give 279. The replacement of a 3-morpholinyl group by a 3-A methyl-A-phenylamino group in thiete 1,1-dioxide is another example of addition-elimination. An addition of ethoxide with elimination of p-nitrophenyl anion may occur with 268 (Ar = / -N02C6H4). " Addition of bromine via N-bromo-succinimide to the double bond of 4-phenyl-2H-thiete 1,1-dioxide occurs only in 1.5% yield. ... 

Refluxing 2,4-diphenyl-2H-thiete 1,1-dioxide in ethanol yields the acyclic sulfone 286. Treatment of naphthothiete sulfone 205b with methyllithium, sodium hydroxide, or lithium anilide gives products, for example, 287, resulting from nucleophilic attack on the sulfur atom of the sulfone... 

Since 3-(/V,Af-dialkylamino)-2H-thiete 1,1-dioxides are enamines, their hydrolysis to 3-ketothietane 1,1-dioxides occurs readily h527,600-602,606 j g hydrolysis of 296). 3-methoxy- and 3-ethoxy-2H-thiete 1,1-dioxides also are hydrolyzed to the keto derivatives. Thiete sulfone does not undergo polymerization with cationic or anionic catalysts. ... 

A 2+2 photochemical cyclization involving the exocyclic carbon-carbon double bond of 2-methylene-4-phenyl-2H-thiete 1,1-dioxide is reported to give a cyclobutane derivative in 12% yield. An attempt to remove bromide ion from 2-bromo-4-phenyl-2H-thiete 1,1-dioxide with silver tetrafluoroborate was unsuccessful. ... 

The sulfur-sulfur interatomic distance in 9-phenyl-4,8,10-trithiadibenzo[cd,ij]a-zulene-8-oxide (417) is significantly shorter than the sum of their van der Waals radii and photolysis of (417) and (418) yields (420) and aldehydes or ketones (421) quantitatively. The unstable primary photoproduct (419) may be isolated and photolyses to (420) and (421). A similarly short sulfur-sulfur interatomic distance is found in a series of naphtho[l,8-ef][l,4]dithiepins and direct irradiation yields naphtho[l,8-cd][l,2]dithioles quantitatively with analogous S-S bond formation and alkene elimination. Photolysis of compounds (422), (424) and (426) gives the dimerised disulfides (423), (425) and (427) in 45%, 17% and 1% yields respectively. Irradiation of the tetraalkyl-2H-thietes (428) at 254 nm leads to a photostationary mixture containing the purple enethiones (429) (25%). Exposure of the mixture to 300 nm radiation induces almost complete reversion to (428). ... 

The bicyclic compound (438), which is formed by [2 4- 2] cycloaddition of 2H-thiete and TCNE in 55% yield (based on the precursor compound of the thiete), rearranges to give the thiophene (439) in high yield, when heated in the non-polar solvent benzene (Scheme 89) <85JOC799>. 

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