The Reaction of Benzenesulfenanilides with Lewis Acids: Involvement of Radical Cation Intermediates.

Article abstract of DOI:10.1016/S0040-4020(01)91226-8

The 4'-substituted N-methylbenzenesulfenanilides 1a-c react with Lewis acids, including BF3, AlCl3 and GaCl3, to afford the radical cation intermediates 9a-c, some of which could be detected by e.p.r. spectroscopy.Thus, the 4'-methoxy substituted compound 1a gave the fairly persistent radical cation 9a.In contrast, the radical cation 9b, derived from the 4'-nitro substituted compound 4b, was not detected apparently because it decayed too rapidly forming the very stable radical cation 11b, intermediate in the formation of the rearranged sulfide 10b.The radical intermediates 9a-c react with cyclohexene to give the 1,2-adducts 4a-c, 5 and 6 which are believed to be formed from either the thiiranium ion 7b or the sulfurane 8a,c.