Bicyclo [3. 3. 1]nonanes as Synthetic Intermediates. IV. Behavior of Bicyclo [3. n. 1] alkan-3-ones toward the Baeyer-Villiger Oxidation

The Baeyer-Villiger oxidation of bicyclo [3. n. 1] alkan-3-ones and related systems is described. Bicyclo [3. 3. 1] nonan-2-one (8) was oxidized into the corresponding lactone, which was found to be converted into the cis-1, 3-disubstituted cyclohexane system by the subsequent methanolysis. Meanwhile, the 3-oxo system (2) manifested an anomalous inactivity against the oxidation. The"backside steric hindrance"caused by the axial (endo) proton at C-7 was postulated as the origin of the inactivity. The differential reactivity of the ketones in the Baeyer-Villiger reaction of the bicyclic systems (2, 3, 4) enabled the regiospecific lactonization of the bicyclic diketones (17, 18, 19) into the lactones (37, 38, 39), which would be important precursors for specifically substituted medium-sized lactones, to be achieved.