Imino Diels-Alder adducts.: II.: Two pyrano[3,2-c]quinolines

8-Chloro-9-fluoro-5-phenyl-3,4,4a,5,6,10b-hexahydro-2H-py-rano[3,2-c]quinoline and 10-chloro-9-fluoro-5-phenyl-3,4,-4a,5,6,10b-hexahydro-2H-pyrano[3,2-c]quinoline, both C-18-H17CIFNO, are diastereoisomers, formed as the result of the imino Diels-Alder reactions of N-benzylideneanilines with 3,4-dihydro-2H-pyran. The crystal structures reveal the stereochemistry of the pyran ring, which is endo/exo to the quinoline ring system formed in the cycloaddition step. In both structures, the pyran ring adopts a chair conformation, while the nitrogen-containing heterocyclic ring prefers a half-chair conformation. The structures differ essentially in the relative orientation of the ring junction H atoms.