Photochemical behavior of iodoheterocyclic derivatives in the presence of electron-poor olefins

Photochemical reactions of some haloheterocycles bearing electron-withdrawi ng groups 1a-d with electron-poor olefins 2a-c gave the addition products 3 a-f and 3h-m in good yields. Other products obtained were the corresponding olefins 4a-k and the alkanes 3g. These reactions involve homolytic cleavag e of the carbon-halogen bond to give the corresponding radical. The nature of these radicals has been studied. Ab initio calculations at the MP2/6-31G * level are supportive of the formation of sigma radicals. These radicals a re electrophilic and interact with the HOMOs of the electronpoor olefins.