Cyclization of Dienes During the Free Radical Addition of Small Molecules

Cyclization of certain perfluoroalkyl-substituted 6-heptene-2-yl radicals to a 5-membered ring product was observed in the free radical reaction of iodoperfluoroalkane and 1,6-heptadiene. This behavior contrasts with that observed in cyclic polymerization which is reported to give 6-membered rings but resembles that recently reported for the 5-hexen-l-yl radical. Many related free radical reactions of 1,6-heptadiene and its analogs with various addenda have been disclosed, and cyclization products from presumably similar radicals have been described in terms of six-membered ring structures. A detailed report of these reactions has not appeared. This report presents a closer examination of this subject in view of the unexpected nature of more recent results. (Author).