A multicomponent, facile and catalyst-free microwave-assisted protocol for the synthesis of pyrazolo-[3,4-<i>b</i>]-quinolines under green conditions

Abstract

A facile, swift and ecofriendly microwave-assisted multi-component/one-pot protocol is designed for the synthesis of novel pyrazolo-[3,4-<i>b</i>]-quinolines at ambient temperature in aqueous ethanol as a reaction medium. The 18 novel pyrazolo-[3,4-<i>b</i>]-quinoline derivatives were synthesized by fusion of chosen aryl aldehyde, dimedone and 5-amino-3-methyl-1-phenylpyrazole in excellent yields (91-98%). All the molecular structures were confirmed by ¹H-NMR, ¹⁵N-NMR, ¹³C-NMR, and HRMS data analysis. Operational simplicity, easy handling, one-step simple workup procedure, mild reaction conditions, short reaction time (≤10 min), high selectivity and no by-product formation are the striking features of the protocol.