Thiete formation

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. 

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. ... 

Irradiation of a thiete 1,1-dioxide in degassed solutions of acetonitrile or dichloromethane at 253 nm leads to the formation of vinyl ketones (241) via... 

As highly reactive heterocycles, the thietes are well suited for the formation of metal complexes. Takahashi and Dittmer both individually and in collaboration have been involved with the interaction of thietes and iron or cobalt carbonyls. During the thermally or photochemically induced complexation process, ring opening takes place so that the resultant thioacrolein is the actual ligand in the organometallic compound (Scheme i7)/ 3-203,204... 

Oxygen can be introduced into the a-positions of thietanes by treatment of the thietane with lead tetraacetate as in the formation of (204) (75JOC3046). Thietanones can be prepared by hydrolysis of thiete enamines such as (205) (65LA(684)103) or by oxidation of 3-thietanol with DMSO/benzoic anhydride (78PS(4)167>. Thietanones can be converted into various ring-substituted sulfur derivatives as already illustrated in reactions of (68) and preparation of (199). 

Examples of reactions of the carbon-carbon double bond of thietes with protic acids are illustrated by the formation of mercaptoaldehyde (42) (72JOC1111), hydrogen cyanide adduct (43) (77JOC3506) and sulfide (44) (62JA399). 

The intermediacy of a thiete, selenete, or tellurete complex in the formation of the heteroacrylamide complexes is further supported by the isolation of several 2//-selenete complexes (132) from the reaction of [W(CO)5 i7f-... 

The treatment of bis(trimethylsilanyl)methanesulfonyl chloride with triethylamine led to the formation of a sulfene 89, which upon reaction with diethyl ketene acetal gave a thietane adduct 90. The latter led to thiete 1,1-dioxide 91 in very poor yield (5%) after the loss of trimethylsilyl ethoxide (Equation 29) <2000CJC1642>. 

The photodecarbonylation reaction of thiophenones 118a-c leading to the formation of alkyl-substituted thietes 119a-c in high yields turned out to be a useful method for their synthesis (Table 12) <1997HCA510>. 

The reaction of 2-methyl-3-thioformylindole 173 with 2-aminoethanethiol led to the formation of the 1,3-dithie-tane 176 in 8% yield, and also two Schiff bases 174 and 175 (Equation 28) <1999RJO1507>. The rather exotic reaction of 4-diethylamino-3-butyn-2-one 177 with l-isothiocyanato-4-nitrobenzene 178 has also been reported <2001SL361>. After 4h of heating in THF of the substrates, the substituted thiete 179 and dithietane 180 were isolated in 46% and 35%, respectively (Equation 29) <2001SL361>. 

Diels-Alder reactions of thiete 1,1-dioxides occur readily as exemplified by the syntheses of 151 ° and 152. Adducts of thiete 1,1-dioxide with tetraphenylcyclopentadienone or a-pyrone ° are thermally unstable. Thiete 1,1-dioxides also undergo 1,3-dipolar additions with diazoalkanes, (e.g., the formation of 153 from which the strained bicyclic thietane sulfone 154 is obtained) " nitrile oxides, and cycloadditions with the MA -dimethylenamine of isobutyraldehyde (e.g., the formation of 155). ° ... 

Photoelectron spectra of benzothiete 209, the ketene derivative 210, (not isolated), and the naphthothiete 205 have been obtained and vertical ionization potentials reported. The unstable thiolactone 211 shows a carbonyl absorption at 1803 cm . ° The mass spectra of thietes usually show the molecular ion minus a hydrogen atom or other group as the most abundant species, thus suggesting the possible formation of a 4 -electron cation, for example, 212. ° ... 

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. ... 

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