Tandem homolytic addition/substitution sequences and their application to tin-free radical chemistry

Alkyl pent-4-enyl selenides (3a, b, e and f), pent-4-enylseleno benzoate (3c) and phenyl (pent-4-enylseleno)formate (3d) act as precursors of alkyl, acyl and oxyacyl radicals by reaction with diethyl 2-phenylselenomalonate (1) under photochemical conditions in a process involving tandem homolytic addition/substitution to afford tetrahydroselenophenes (5, 11) and the corresponding phenylselenides (6).