Sulphenyl halides olefins

The A -unsaturated-5a-thiol (350) reacted with bromine or chlorine to give the 3j8-halogeno-2a,5a-epithio-derivative (353). ° It is suggested that a 5a-sulphenyl halide e.g. (351)] is first formed, and then attacks the olefinic bond to give the sulphonium ion (352), which suffers nucleophilic attack upon C(3) by halide ion. Lead tetra-acetate similarly afforded the 3j8-acetoxy-2a,5a-epithio-compound. 

The order of susceptibility towards substituent effects is much less in the acetylene series than in the olefins, but its direction is similar. A similar statement may be made about the direction, rates, and kinetics of addition of sulphenyl halides. While the simple acetylenes, such as sym-diphenylacetylene and 3-hexyne, required catalytic quantities of aluminium chloride before undergoing addition by 2,4-dinitrobenzene sulphenyl chloride , the rates of reaction of acetylene itself with some p-substituted benzene sulphenyl chlorides alone have been measured. The effect of the p-substituents... 

Reviews cover the topics alkynethiolates in synthesis " oxygen-exchange reactions of sulphoxides sulphonyldiazomethanes C—S bond cleavage acyl isothiocyanates radical reactions of sulphur compounds addition of sulphenyl halides to olefins " sulphenamidcs mercaptoethylation of amines sulphur as a chiral centre " stereochemistry of S and S " compounds " reductive cleavage of sulphides, synthetic uses of alkene- and alkyne-thiolates, and thio-Claisen rearrangements nucleophilic displacements at sulphur in disulphides aromatic... 

Addition of positive sulphur species, RS", usually derived from sulphenyl halides, to olefins is commonly assumed to proceed by way of thiiranium ions, the reactions often showing the stereochemistry expected for trans-addition For instance, the reaction of cyclohexene with methanesulphenyl tetrafluoroborate is believed to form an intermediate thiiranium ion (73), which then reacts with nucleophiles to give trans-methylthio-derivatives, e.g. (74). Addition of thiocyanogen chloride to olefins may... 

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