Cyclohexane-1, 3-dicarboxylic anhydrides (IVa-c), prepared from isophthalic acids in several steps, were treated with diethyl magnesiomalonate and triethylamine to give 3-di (ethoxycarbonyl)-acetylcyclohexanecarboxylic acids (Va-c) in good yields. Compounds Va-c were converted into methyl 3-acetylcyclohexanecarboxylates (VIa-c) by decarboxylation and esterification. Cyclization of VIa-c to bicyclo [3.3. 1] nonane-2, 4-diones (I) was performed ...