In the presence of catalytic amounts of molecular iodine and stoichiometric potassium persulfate, a green, highly chemoselective, regioselective and cis-selective radical isothiocyano-chalcogenization of alkenes with NH₄SCN in water is disclosed. This three component reaction features high selectivities, an environmentally benign process, mild conditions, high yields, excellent functional-group tolerance, and broad substrate scope. The resulting products can be further transformed into other molecules with structural similarities of these compounds to bioactive analogs.