Efficient synthesis of fused benzo[b] indazolo[6,7-h] [1,6] naphthyridines

Adhiyaman Kottai Munusamy Mage

Abstract

This paper describes the synthetic route to benzo[b]-1H-Indazolo[6,7-h][1,6]naphthyridine-7[6H]-ones, from 2- chloroquinoline-3-carbaldehydes. 2-chloroquinoline-3-carbaldehydes prove to be excellent starting material for the synthetic sequence.2- chloroquinoline-3-carbaldehydes were converted into 2-oxo quinoline-3- carbonyl chlorides from reported literature method. The carbonyl chloride condensed with 1H-Indazole-6-amine led to the formation of 3-(6'-amido-1'H-Indazolo)quinoline-2-[1H]-one. The cyclisation of 3-(6'-amido-1'H-Indazolo) quinoline-2-[1H]- one with PPA resulted the cyclised benzo[b]-1H-Indazolo[6,7-h][1,6]naphthyridine-7[6H]-ones. The reaction sequence was generalized and was extended to synthetic derivatives. All the synthesized compounds were unambiguously identified on the basis of their spectral data analyses.