Synthesis and NMR study of norbornane/norbornene-fused tetracyclic azetidinones

Tetracyclic azetidinones$\text{8}$,$\text{9}$ and $\text{12}$–$\text{17}$ were synthesized. In the cases of$\text{8}$ and$\text{9}$, the main component was isolated from the two-component product of the cycloaddition. The minor component was concentrated to give a mixture, from which a computer technique utilizing the known spectrum of the main component gave the proton resonance spectrum also of the minor component. Only one diastereomer could be isolated for the each of the analogues$\text{12}$–$\text{17}$. Reaction of the 1,3-oxazine $\text{3}$ with chloroacetyl chloride gave, besides the azetidinone $\text{12}$, the 1,3-oxazine 2,3-$\text{b}$]-1,3-oxazin-4-one derivative$\text{18}$. Configurations and conformations were determined by IR, ¹H and ¹³C NMR spectroscopy.