The reaction of 5, 5-dimethyl-l, 3-~ yclohexanedione (1) in form of its Na-salt with diphenylcyclopropenone (2) in DMF yielded the bicyclic triketone 3 (58%), the structure of which was deduced as an enolizeable bicy-clo [5.2. 0] nonane-, b'-diketone from spectral data and from the following reactions: hydrolysis or methanolysis of 3 cleaved the P- dicarbonyl moiety, thereby opening the 4-membered ring to yield the keto acid 9 or its ...
![4,4-dimethyl-7,8-diphenylbicyclo[5.2.0]nonane-2,6,9-trione Structure](https://image.chemsrc.com/caspic/422/106661-50-1.png)