C-13 MAGNETIC-RESONANCE STUDIES .144. AN EXAMINATION OF BETA-ENOLIZATION IN THE BICYCLO[3.3.1]NONAN-2-ONE AND [3.2.2]NONAN-2-ONE SYSTEM

While 3,3-dimethylbicyclo[3.3.1]nonan-2-one (5) is stable under strong ly basic conditions (t-BuO-/t-BuOH/185-degrees-C), its isomer, 3,3-dim ethylbicyclo[3.2.2]nonan-2-one (6), is slowly transformed to S. Simila rly, 3.3-dimethylbicyclo-[3.2.2]non-6-en-2-one (8b) rearranges to a [3 .3.1] isomer but the latter is not stable. Experiments with 3,3-dimeth yl-bicyclo[3.3.1]non-6-en-2-one (7) revealed that it is converted to f ive compounds, none of which is 8b. The major product, 8,8-dimethylbic yclo[4.3.0]non-1(6)-en-7-one (11) arises from beta-enolate rearrangeme nt. Enone 11 undergoes slow reduction to cis- and trans-8,8-dimethylbi cyclo[4.3.0]nonan-7-one, presumably by single electron transfer. Exper iments with 11 alone showed that beta-enolate rearrangement of 7 --> 1 1 is unidirectional. Haller-Bauer cleavage to acidic products occurs a s a minor process in the reactions of the unsaturated ketones. The str uctures of the products were established primarily from their H-1 and C-13 magnetic resonance spectra.