Aryl vinyl sulphoxides

TABLE 26. Michael additions to aryl vinyl sulphoxides... 

Dialkyl cuprates may also be added to aryl vinyl sulphoxides and the resulting a-sulphinyl carbanions can be treated with various electrophiles such as aldehydes, ketones and alkyl halides (equation 350)643. 

Aryl vinyl sulphones, reactions of 646 Aryl vinyl sulphoxides 620 optical resolution of 287 reactions of 354, 355, 360, 361, 621 Asscher-Vofsi reaction 189 Asymmetric induction 625 Asymmetric oxidation 72-78 Asymmetric reduction 78, 79 Asymmetric synthesis 824-846 Atomic orbitals 2, 3 Azetidinones 790, 791 ot-Azidoaldehydes, synthesis of 811 Azidosulphones, photolysis of 883, 884 Azosulphones, photolysis of 879 Azoxysulphones, photolysis of 879 1-Azulyl sulphoxides, synthesis of 265... 

Pyrolysis of aryl sulphoxides gives rise to alkenes. Coupled with Michael addition of nucleophiles to aryl vinyl sulphoxides, a rather general synthesis of substituted alkenes results. Annulenophanes have been prepared by photolytic triethyl phosphite-induced desulphurization of cyclic bis-dialkylsulphides. ... 

The catalysed -elimination of hydrogen bromide from 2-bromoethyl and 1,2-dibromoethyl sulphides, using 9.1.1 or 9.1.2, provides a convenient route to vinyl and alkynyl sulphides, respectively [17, 18], which, as their sulphoxides or sulphones, have considerable utility as dienophiles. Aryl vinyl ethers (>90%) have been obtained by analogous procedures from 2-chloroethyl ethers [19]. 

A condensation of vinyl sulphides of synthetic value involves the reaction of a-ethylthio-styrenes with an aldehyde in the presence of a Lewis acid catalyst to give 3-ethylthio-indenes. Regiospecific and stereospecific pentannelation i.e, fusion of a cyclopentane ring) of an alicyclic ketone involves arylthiomethylen-ation followed by base-catalysed addition to an aj8-unsaturated ester. a-Phenyl-thiobutenolides are less reactive Michael acceptors than their sulphoxide counterparts, and /SjS-dichlorovinyl sulphides are less reactive in electrophilic reactions than their oxygen counterparts. Dimerization of aryl a-cyanovinyl sulphides occurs more readily than that of alkyl analogues, since the intermediate 1,4-diradical ArSC(CN)CH2CH2d(CN)SAr, which cyclizes to the cyclobutane, is more stable. Products obtained by photolysis of methyl vinyl sulphide are accounted for by homolysis of both vinyl—S and methyl—S bonds. The kinetics of catalysed cis-trans isomerization of aryl vinyl sulphides have been studied. ... 

Unsaturated Sulphoxides.—Variations of known methods for the synthesis of vinyl sulphoxides are described in reports of asymmetric selectivity in the elimination of HCl from jS-halogenoethyl aryl sulphoxides using an optically active base, leading to partially resolved vinyl sulphoxides, and in reports of the condensation of carbonyl compounds with (Et0)2P(0)CHaS(0)R in the presence of a phase-transfer catalyst. Vinyl sulphoxides are formed when sulphenic acids are trapped after generation in the presence of an acetylenic ester, and a full account is available of the trapping of the sulphenic acid of... 

The base-catalysed cis-trans isomerization of l-aryl-2-phenylcyclopropanes has been subjected to kinetic analysis and a complexed anion, e.g. (190), is thought to be produced initially. Configurational inversion of the cyclopropyl sulphoxide (173) can also be effected by base. A kinetic analysis of the hydrolysis of 2- and 2,2-di-substituted bromocyclopropanes suggests that for 2-vinyl-substituted compounds considerable progress towards an allyl cation has been been made at the transition state. Metallation studies show that, for nortricyclanes at least, the cyclopropyl hydrogen atoms are most readily attacked by pentylsodium in the presence of potas-... 

Fundamental information on bonding is provided by photoelectron spectroscopy of thioanisoles and other alkyl aryl sulphides. Two conformers are predominant for these compounds, RSPh, and the proportion of the conformer with maximum overlap decreases through the series R = H, Me, Et, Pr or Bu. Related studies for sulphoxides provide correlation diagrams for the effects of substituents R in RS(0)R, as well as information on preferred conformations. An orienting survey of hexavalent sulphur functional groups, viz. alkyl, vinyl, and aryl sulphones, S -dialkyl sulphimides, sulphuryl halides, sulphoximides, and sulphurdi-imides, is available. ... 

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