Thiete 1,1-dioxides ring-opening

Base-induced eliminative ring fission, in which both the double bond and the sulfone function take part, has been observed in thiete dioxides . The reaction can be rationalized in terms of initial Michael-type addition to the double bond of the ring vinyl sulfone, followed by a reverse aldol condensation with ring opening. The isolation of the ether 270c in the treatment of 6c with potassium ethoxide (since the transformation 267 268 is not possible in this case) is in agreement with the reaction mechanism outlined in equation 101 . 

H-Benzo[6]thiete synthesis, 4, 824 Benzothietes ring opening, 7, 423 synthesis, 4, 824 Benzothietide anions stability, 7, 419 1H-1 A4-1 -Benzothiins pxidation, 4, 969 stability, 3, 926 structure, 3, 894 Benzothiins, dihydrodisproportionation, 3, 908 lH-2-Benzothiin, 3,4-dihydro-2,2-dioxide... 

The mass spectra of several thiete sulfones have been interpreted on the basis of ring-opening to the cyclic sulfinate (sultine). Benzothiete sulfones lose sulfur dioxide to give benzocyclopropenium ions. The peri effect in 1,8-disubsti-tuted naphthalene derivatives, for example, 205b, has been discussed. ... 

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 thietane ring of the carboxylate derivative 352 is apparently opened by loss of carbon dioxide. possibly via a thiete intermediate. Isonitriles and ynamines effect ring-expansions of 2,4-bis(imino)thietanes, and similar reactions of enamines and ynamines with tris(imino)thietane, 353 have been reported. The nucleophiles — methanol, ethanethiol, and diethylamine — attack the a-carbon atom of 353, which bears the iminosulfonyl group, to give ring-opened products, for example, 353a. The reactions with sodium azide or hydrazoic acid take a different course. ... 

Electrocyclic ring opening of thiete 1,1-dioxide (34), in both the vapor and liquid phases, readily yields vinylsulfene (35) which, as is indicated in equation 26, is either trapped to form a characteristic product (e.g. 36), cyclizes to the sultine 37, or, in the gas phase at high temperature, desulfinylates to acrolein118 (Section V.C.). Vinylsulfene (35) produced from 34 also reacts with [2.2.1]bicycloheptene to form the [2 + 4] cycloadduct (38)119. 

Mention has already been made in Section III of the photochemical formation of sulfene from thietanone 1,1-dioxide19, presumably by a [2 + 2] cycloreversion. Lan-gendries and DeSchryver have also observed photochemical electrocyclic ring opening of thiete 1,1-dioxides, e.g. 42, forming either the products of desulfinylation or sulfene trapping122, as in equation 31. 

No evidence could be obtained for the formation of 2ff-benzo[i>]thiet or its valence tautomer by irradiation of 3/f-l, 2-benzodithiole l,l-dioxide. Naphtho-[l,8-6c]thiet (58) has been prepared and its 5-oxide, and S -dioxide, have been obtained by oxidation with m-chloroperoxybenzoic acid. All three compounds react with lithium aluminium hydride to give ring-opened products as the result of hydride attack on sulphur. After reduction and methylation, (58) gave the methyl sulphide (59), and the 5-oxide gave bis(a-naphthyl) disulphide (75%) together with (58) (6%) and the corresponding sulphone (4%), which was the major product (85%) from the 55-dioxide (Scheme 8). Thiets are believed to be... 

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