Allyl sulphones rearrangement

Isomerizations and Rearrangements An optically active allylic sulphone has been generated via a... 

The phenyl analogue likewise gave a high yield of benzoylethylene. Along the same line, King and Harding have reported a sulpho-Cope rearrangement which appears to involve sulphene formation. Vinyl allyl sulphone, when heated to 170 °C in the liquid phase or to 800 °C in the gas phase, probably was converted into the sulphene (87). In the gas phase, pent-4-enal was isolated, whereas in the liquid phase addition of phenol led to a phenyl sulphonate. 

Allylic sulphones are available through the reaction of a t-butyl sulphoxide and an allyl alcohol with A -chlorosucdnimide, and through the reaction of an allyl alcohol with di(AT-phthalimido) sulphide or di(iV-imidazolyl) sulphide to give a sulphoxylate, e.g. CHa=CHCH20S0CH2CH=CH2, which rearranges to the bis(allyl) sulphone by way of the sulphinate. Further study of the rearrangement of iV-aryl arenesulphonamides to iV-(u-aminoaryl) aryl sulphones has been described. ... 

Thermal pericyclic rearrangement of an aryl allyl sulphone ArSOzCR R -CR =CR R at ca. 290 C places the aryl substituent at the y-position of the allylic system, SO2 being eliminated to give ArCR R CR =CR R. Isomerization to the vinyl sulphone can occur with t-butyl allyl sulphones on treatment with K2CO3 in acetone. 

Continuation of studies aimed at preparing sulphenes by pyrolysis of sulphonyl derivatives has involved the allyl vinyl sulphone (134), which on heating at 170 °C in the liquid phase, or at 800 °C in the gas phase, gives products derived from the sulphene, itself arising through a sulpho-Cope [3,3]sigmatropic rearrangement. ... 

Dehydration of compounds (653 R = H or Ph) by toluene-p-sulphonic acid in benzene proceeds by homo-allylic rearrangement to give (654 R = H or Ph) some unrearranged olefin is obtained in the dehydration of (653 R = Ph). The cycliza-tion of ethyl (cyclo-oct-4-enylidene) acetate with BFajOEtj in hot benzene affords (655) and the corresponding acid (656). The bridgehead cation (657) is the presumed reaction intermediate. Aluminium chloride-catalysed cyclization of the lactone (658) resulted in the stereospecific formation of the carboxylic acid (660) the epimeric lactone (659) produced a mixture of a hexahydrofluorene carboxylic acid and the epimeric benzobicyclononene acid (661) mechanisms are discussed. 

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