Reversible coupling of a substituted allylic radical with molecular oxygen in a toco reaction of 5-methylhepta-1,3,6-triene

p-Toluenethiol/oxygen co-oxidation of 5-methylhepta-1,3,6-triene (1) gives inter alia only one (6a) of four possible diastereoisomeric dioxolanes, and the threo- and erythro- isomers of the 1,4-addition product (10, 11). The variation in relative yields with thiol concentration indicates that coupling of the allylic radical (2) with oxygen is reversible. © 1983.