Free-radical, Carbene, and Photochemical Reactions

Martin and his co-workers have provided a firm experimental foundation for anchimeric assistance in the homolytic decomposition of per-benzoate derivatives (Table 6). A single o-phenylthio group was found to increase the rate of decomposition of f-butyl perbenzoate by a factor of ca. 45 thousand. The effect is not steric since an o-r-butyl group hardly affects the rate of perester decomposition [compare (95) versus (99), Table 6]. A noticeable but weak effect is observed with the homologous sulfide (96). In addition to sulfur, anchimeric assistance by iodine and vinyl groups in (97) and (98), respectively, was observed. The bridged canonical species 

Sulfonium ions have been suggested as intermediates in the photolysis of cyclic y-keto sulfides on the basis of product studies. For example, the irradiation of thiacyclohexan-4-one (107) in f-butyl alcohol gave the 

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