S-Alkyl and S-acyl xanthates are valuable sources of alkyl and acyl radicals which can be trapped inter-or intra-molecularly b y various alkenes in a radical chain process.

ChemInform Abstract Photolysis of the S-benzoyl xanthate (Ia) and allyl acetate (II) yields the adducts (III) and (IV) which are transformed into the α,β-unsaturated ketone (V). The methylenechromanone (VIII) is prepared by an analogous intramolecular reaction of the allyloxybenzoyl xanthate (VI). N-Benzylmaleimide (IX) and phenyl vinyl sulfone (XI) are irradiated in the presence of (Ib), forming the xanthates (X) and (XII).