Model Studies of β-Scission Ring-Opening Reactions of Cyclohexyloxy Radicals:  Application to Thermal Rearrangements of Dispiro-1,2,4-trioxanes

A DFT study of model cyclohexyloxy radicals (8a−c, 9) show that (a) the presence of an adjacent oxygen atom, and (b) α-substituents on the cyclohexyl ring, particularly methoxy, accelerate the rate of β-scission ring-opening reactions. Consistent with theoretical results, thermolysis of the methoxy-substituted dispiro-1,2,4-trioxane 10 afforded the structurally novel, 14-membered macrocyclic keto lactone 11 as the major isolable product.