Sulphinates rearrangement

Allyl sulphenates, rearrangement of 720-736 Allylsulphenic acids 747 Allyl sulphinates, rearrangement of 670-676 Allylsulphinyipyrazolenines, photolysis of 749... 

Despite the aversion of the sulphonyl group to function as a nucleophile, there are a limited number of literature reports that deseribe sueh a process . The first of these does not lead to a reduetion at sulphur and is thus not direetly relevant, but the report by Braverman and Duar deseribes reaetions in whieh an acetylenie sulphinate ester ean undergo a [2,3] sigmatropie rearrangement to an allenie t-butyl sulphone. Reaetion of this sulphone with the appropriate eleetrophile, for example bromine, gave a y-sultine, formation of whieh requires the partieipation of the sulphonyl group in an intramoleeular cyclization process. The reactions are outlined in equation (40). 

The [4 + 2] cycloaddition of a-phenylselenopropenoyl trimethylsilane (75) with 2,3-dimethylbuta-1,3-diene is unusual in that a significant portion of product mixture consists of the hetero-Diels-Alder dihydropyran adduct 76. The phenylselenenyl substituent appears to be responsible for this unusual pattern of reactivity, since propenoyl trimethylsilane gives only the expected regioisomer (77, X = H) (Scheme 116)14. a-Selenenyl substituted a,/l-unsaturated acyl silanes such as 75 were used to prepare a series of substituted dienes in excellent yields through the addition of a-sulphinyl carbanions, Brook rearrangement and expulsion of sulphinate, in a reaction pathway recognisably more typical of acyl silanes (Scheme 117). 

Braverman, S. The chemistry of sulfinic acids, esters and their derivatives. Rearrangements. Chem. Sulphinic Acids, Esters Their Deriv. 1990,297-349. 

The formation of the dialkyl (2-oxoalkyl)phosphonates (539) illustrates the regioselec-tive nucleophilic attack by phosphite anion, with rearrangement and displacement of sulphinate anion, applicable when R = C1-C5 alkyl and R = H, Me or Ph in the single case when Ar = Ph, R = H and R = Ph, the product was diethyl (2-phenylethenyl)phospho-... 

Alternatively, the allyl sulphinyl anion (8) gave the threo adduct (9), which underwent sulphoxide - sulphinate ester rearrangement, leading to the hex-2-enitol derivative (10)(Scheme 4) the threo isomer predominated by non-chelation control, which has previously been difficult to achieve. ... 

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... 

Preparations from sulphinic acids, SO2, other simple sulphur compounds, and sulphonyl halides are reported in the papers that are listed (with brief details) at the end of this section. The AlClj-catalysed rearrangement of an aryl arenesulphonate gives the corresponding diaryl sulphone. ... 

CHMel/ thus supporting the interpretation of rearrangements of alkenes in liquid SO 2 that is based on the instability of allyl sulphinic acids. Sodium salts of sulphinic acids take the role of co-catalyst in PdClj-catalysed dimerization of butadiene in an alcohol solvent, leading to octa-2,7-dienyl alkyl ethers, and act as arylating agents towards cyclo-octa-1,5-diene in the presence of PdClj. ... 

The principal component of the lachrymatory factor of the onion (Allium cepa) has been identified by flash vacuum pyrolysis (FVP)/microwave techniques as (Z)-propanethial 5-oxide, CH3CH2CH=S=0. It functions as a 1,3-dipole and as a dipolarophile, and it dimerizes in cold benzene to give principally trans-3,4-diethyl-1,2-dithietan 1,1-dioxide rather than 2,4-diethyl-1,3-dithietan 1,3-dioxide, as previously proposed. Formation of this sulphine from its cellular precursor, rran5-(+)-S-(prop-l-enyi)-L-cysteine sulphoxide, is suggested to involve the formation of a Schiff base and the elimination of ( )-prop-l-enesulphenic acid, which then rearranges to the sulphine (Scheme 2). 

Reactions.—Condensation of thiet sulphone with 2 moles of halogeno-hydrazones, RC(Cl)=NNHPh, gives isoimidazoles (113). Cycloaddition of thiet sulphone to cyclopentadiene occurs with an exofendo ratio of 0.25. 2,4-Diphenylthiet dioxide is hydrolysed to dibenzyl sulphone with base, but rearranges to the isomeric sulphinate 3,5-diphenyl-1,2-oxathiolen 2-oxide with concentrated sulphuric acid. Treatment of 4-phenyl-2i/-thiet 1,1-dioxide with KOH in ethanol gives 3-ethoxy-2-phenylthietan 1,1 -dioxide. ... 

Dithietans.—1,2-Dithietan (114) is the first isolated derivative in that class. It arises by dimerization of ethyl sulphine, probably by rearrangement of a first-formed sulphenyl sulphinate (see Chap. 3, Pt. II, p. 161). 

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