New Procedure for the Transformation of Alcohols to Alkyl Halides via Xanthate Esters and Free-Radical Intermediates

Article abstract of DOI:10.1021/jo00340a028

O-Alkyl-S-methyl xanthates have been used to convert alcohols to alkyl halides via free-radical pathways.The xanthate esters were readily prepared in high yields and were converted in 8-80percent yields to the corresponding alkyl halides by (a) photolysis with 254-nm light in carbon tetrachloride or bromotrichloromethane and (b) by treatment with Cu(I)-Cu(II) halide in acetonitrile.The photochemical transformation gave low yields with highly aliphathic compounds due to carbon tetrachloride-mediated free-radical halogenation reactions.The transformation promoted by Cu(I)-Cu(II) halide competed with an electron-transfer oxidation process.The reaction could not be induced with AIBN or benzoyl peroxide or by treatment with molybdenum pentachloride.Mechanistic implications are discussed.