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) a-substituents on the cyclohexyl ring, particularly methoxy, accelerate the rate of ß-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. © 2007 American Chemical Society.