Synthesis of 3, 4-dihydro-5H-pyrido [4, 3-b] indoles and 3, 4- dihydropyrimido [3, 4-a] indoles

Department of Chemistry. Karnatak University, Dharwar-3

Manuscript received 5 September 1974; accepted 20 January 1975

The Bischler-Napieralski cyclisation of N-benzoyl derivatives of 7-halo-substituted 2-(2-amino­ethyl) indoles employing polyphosphate ester resulted in the formation of 1-phenyl 3,4-dihydro­ 5H-pyrido [4,3-b] indoles. When the 7 position of N-benzoyl derivatives of 2-(2-aminoethyl)indoles was unsubstituted, cyclisation took place in 1 position to give 1-phenyl 3,4-dihydropyrimido[3,4-a]­indoles exclusively.