Reactions of the methylthiyl radical with unsaturated cycloalkanes: abstraction, addition, and rearrangement

The methylthiyl radical (MeS˙) generated by photolysis of dimethyl disulphide (MeSSMe) is shown to give three types of reactions with cyclic molecules containing carbon–carbon double bonds. E.s.r. spectra corresponding to radicals formed by addition of MeS˙, by hydrogen abstraction, and by a rearrangement (possibly involving 1,4-hydrogen shift between SMe and the radical centre) have been detected. In the case of cyclopentene, all three types of radicals were observed. In the case of cyclohexene, only radicals due to abstraction and rearrangement were detected. With methylenecycloalkanes there was no evidence for hydrogen abstraction but radicals from addition and rearrangement were identified.