Synthesis of Novel Pyrido[3′,2′:5,6]thiopyrano[3,2-b]indol-5(6H)-ones and 6H-Pyrido[3′,2′:5,6]thiopyrano[4,3-b]quinolines, Two New Heterocyclic Ring Systems.

The synthesis of new pyrido[3′,2′:5,6]thiopyrano[3,2-b]indol-5(6H)-ones was accomplished by the Fischer-indole cyclization of some 2,3-dihydro-3-phenylhydrazonothiopyrano[2,3-b]pyridin-4(4H)-ones, obtained from the 2,3-dihydro-3-hydroxymethylenethiopyrano[2,3-b]pyridin-4(4H)-one, by the Japp-Klingemann reaction. 6H-Pyrido[3′,2′:5,6]thiopyrano[4,3-b]quinolines were obtained by reaction of 2,3-dihydrothiopyrano-[2,3-b]pyridin-4(4H)-ones with o-aminobenzaldehyde or 5-substituted isatins. The preparation of some derivatives, functionalized with an alkylamino-substituted side chain, is also described.