The electrophilic addition of organosulphur compounds to alkenes is reviewed. The oxidative electrophilic addition of diphenyl disulphide [using manganese (III) acetate as the oxidant] to a series of alkenes carrying a range of remote nucleophilic groups is described. For example the alkenes investigated carry either amide, urea, thiourea, carbamic acid, carbamimidothioic acid, carbondithioic acid, carbontrithioic acid, guanidine, and sulphonamide functionalities. On the addition of diphenyl disulphide these alkenes afford a number of novel cyclic and acyclic sulphur substituted compounds. A review is made of the literature background to the electrophilic addition-cyclisation reaction of iodine with alkenes carrying remote nucleophiles. A number of novel iodosubstituted heterocyclic compounds are efficiently synthesised via the addition of iodine to alkenes carrying either thiourea, carbamimidothioic acid, carbontrithioic acid, and guanidine functionalities. The principle factors determining the mode of these cyclisations are discussed. Dehydroiodination of these compounds affords a variety of novel unsaturated heterocycles. A route through to 5-methylenedihydrothiaxolamines, 6-methylenedihydrothiaxinamines, and 6-methylenetetrahydropyrimidines, and related compounds, having synthetic potential as both nucleophiles, and electrophiles is established. Related reactions with anaolgous methylene lactones, methylenethiaxoles, methylenedihydro-oxazoles, and methylene cyclic carbonates are noted. Further elaboration of the iodosubstituted heterocycles by the substitution of iodine with carbon, nitrogen, oxygen, and sulphur nucleophiles is reported. Examples are given of carbon-carbon bond formation, via free radical substitution reactions, using organotin chemistry.