A variety of polyhydro-6-aryl- and heteroarylcycloalka[b][1,S]naphthyr
idines have been efficiently prepared by thermally induced ring contra
ction of pyrido[2,3-b][1,5]thiazepines obtained by reacting lithiated
2-chloro-N-cycloalkylidene-3-pyridinimines with suitable O-ethyl thioc
arboxylates.