Synthesis of pyrido[3,2,1-de]-phenanthridine derivatives

The title compounds have been prepared (i) by cyclization of N-acyl-8-phenyl-l,2,3,4-tetrahydroquinoline derivatives, and (ii) by a Pschorr reaction on N-(2-aminobenzoyl)-l,2,3,4-tetrahydroquinolines. In the Pschorr reaction the decomposition of the diazonium salts X>f the amines is shown to result in intramolecular diary 1 coupling, affording the pyridophenanthridones and phenolic products, N-salicyloyltetrahydroquinolines. The structures of the various pyrido-phenanthridines synthesized by the two methods have been corroborated by NMR, IR and UV spectral data. A similar Pschorr reaction on N-(2-aminobenzenesulphonyl)-l,2,3,4-tetrahydro-quinoline affords a tetracyclic sulphone analogue of phenanthridone. Results of. attempts to prepare pyrrolophenarithridine derivatives are presented and rationalized. The NMR spectral data of N-acyltetrahydroqiiinoline derivatives used in the preparation of pyridophenanthridine by the cyclization method (i) show slow inversion of the tetrahydropyridine ring compared to tetrahydroquinoline or its 8-phenyl derivative. On the basis of NMR data structures (VIII) and (IX) have been assigned to N-acetyl- and N-chloroacetyl-8-phenyl-l,2,3,4-tetrahydroquinolines respectively