Acid-catalyzed reactions of six- and seven-membered cyclic hemiperacetals and peracetals and of related bicyclic ozonides

HCl-catalyzed reactions of the hemiperacetals 3-methoxy-3-methyl-7-hydroxy-1,2-dioxepane (1a) and 3-methoxy-3-methyl-6-hydroxy-1,2-dioxane (1b) and of the related ozonides 1-methyl-6,7,8-trioxabicyclo[3.2.1]octane (2a) and 1-methyl-5,6,7-trioxabicyclo[2.2.1]heptane (2b) gave peroxidic monocyclic (11—13), bicyclic (14), and (or) tricyclic (15) products. By contrast, reactions of the peracetals corresponding to 1a and 1b, viz., 3-methyl-3,7-dimethoxy-1,2-dioxepane (13a) and 3-methyl-3,6-dimethoxy-1,2-dioxane (13b) gave only non-peroxidic products. Reactions of the persubstituted peracetals 3,6-dimethoxy-3,6-dimethyl-1,2-dioxane (25) and 3,6-dimethoxy-3-isopropyl-6-methyl-1,2-dioxane (27) also gave non-peroxidic products, which resulted from fragmentation of the carbon skeletons.