Pyrazolo-fused quinoline analogues: Synthesis of 1H-pyrazolo [3, 4-b] quinolines and 3-amino-1H-pyrazolo [3, 4-b] quinolines from 3-formyl and 3-cyano-2-chloroquinolines

Abstract

Stepwise synthesis of 1H-pyrazolo [3, 4-b] quinolines 6 has been described from the reactions of 2-chloro-3-formylquinolines 1 with ethyleneglycol and hydrazine hydrate reagents in sequence followed by hydrolysis with BiCl 3. However, 3-amino-1H-pyrazolo[3, 4-b]quinolines 7 have been synthesized from 2-chloro-3-cyanoquinolines 2 with excess of hydrazine hydrate in one step. The functional group manipulation of amino group in compounds 7 has also been studied.