The cis-cxo-amino acid c with norbornene skeleton was converted into 2-aryvl-cis-cxo-1, 3- oxazin-4-ones 5a-d. These compounds, similarly to the diendo isomers 1a-d studied by us earlier, undergo retrodiene decomposition under mild conditions to give 2-aryl-62-l, 3-oxazin- 6-ones (2 ad) in 50-60% yield. The ratio of the decomposition rate constants of the tricyclic diendo and diexo-1, 3-oxazin-4-ones, measured in toluene solution, is about 2.
![(1S,2R,3S,4R)-3-(4-methylbenzamido)bicyclo[2.2.1]hept-5-ene-2-carboxylic acid结构式](https://image.chemsrc.com/caspic/280/91813-47-7.png)
![(1R,2S,3R,4S)-3-(3,4-dichlorobenzamido)bicyclo[2.2.1]hept-5-ene-2-carboxylic acid结构式](https://image.chemsrc.com/caspic/204/91813-49-9.png)
