p-TSA Catalyzed Synthesis of Tetrahydrobenzo[g]quinolines via Multicomponent Reaction using Pyrazole Aldehyde, Lawsone, β-Ketoesters and Ammonium Acetate

Abstract

An efficient protocol has been developed for the multicomponent synthesis of tetrahydrobenzo[g]quinoline-3-carboxylate derivatives using p-toluenesulfonic acid (p-TSA) as catalyst through one-pot four component condensation reaction of pyrazole aldehyde, Lawsone, β-ketoesters and ammonium acetate in ethanol. The synthesized compounds were characterized by spectroscopic techniques.

p-Toluenesulfonic acid-promoted organic transformations for the generation of molecular complexity

“…Pramesh et al revealed the catalytic ability of p -TSA for synthesizing tetrahydrobenzo[ g ]quinoline-3-carboxylate derivatives from pyrazole aldehyde, β-ketoesters, Lawsone, and ammonium acetate by four-component coupling (Scheme 29). 42 This sustainable method is appropriate for a variety of substituted pyrazole aldehydes to afford the corresponding tetrahydrobenzoquinolines in good to excellent yields under reflux conditions in ethanol.…”