Vinyl sulphoxides nucleophilic addition

Halogenovinyl sulphoxides 551 react with nucleophiles to give -substituted vinyl sulphoxides 552. The first step in the reaction is a Michael addition, followed by an elimination of a halide anion605,627 (equation 351). 

Nucleophilic addition to allenyl sulphoxides 547 proceeds across the a, /(-double bond to produce the corresponding )3-substituted allylic sulphoxides which undergo readily a [2,3]-sigmatropic rearrangement affording substituted allyl alcohols (equation 345). Under proper basic conditions, the initially formed allylic sulphoxides can rearrange to the corresponding vinyl sulphoxides which can be elaborated to 2,4-dienones 549 (equation 346) and a-ketosulphoxides (equation 347) . ... 

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. ... 

Asymmetric induction is a factor in nucleophilic and electrophilic additions to a chiral vinyl sulphoxide. " A full account is available of asymmetric syntheses involving the addition of piperidine and of bromine to chiral propenyl and vinyl p-tolyl sulphoxides, respectively (see Vol. 2, p. 50). An observation enhancing the value of a vinyl sulphoxide enantiomer in organic synthesis concerns the control exerted by the metal counterion in Michael addition of the diethyl malonate carbanion to (/ )-(+)-/ra/w-)S-styryl p-tolyl sulphoxide (58). The K-i- and Na salts in EtOH lead to a diastereoisomer mixture in which (59) predominates, while the Li+ salt in THF as the reaction medium leads to a preponderance of the epimeric adduct. ... 

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