Microwave Assisted Synthesis of ethyl-quinolon-4-one-3-carboxylates and Hydrolysis to quinolon-4-one-3-carboxylic Acids

Abstract

A fast and efficient microwave assisted synthesis of several ethyl-quinolon-4-one-3-carboxylates and quinolon-4-one-3-carboxylic acids has been developed. The 3-carboethoxy quinolones are easily obtained in a one-pot procedure through the cyclization of aminomethylenemalonate intermediates obtained by reaction of different p-substituted anilines and diethyl-ethoxymethylenmalonate. These quinolones are then irradiated under base hydrolysis conditions to get the carboxylic acids through a very fast and clean approach.

Synthesis and preliminary structure-activity relationship study of 2-aryl-2H-pyrazolo[4,3-c]quinolin-3-ones as potential checkpoint kinase 1 (Chk1) inhibitors

“…A set of 2-aryl-2 H -pyrazolo[4,3- c ]quinolin-3-ones (PQs) was synthesised from ethyl-quinolin-4-one-3-carboxylates using a protocol previously published by our research group 49 . The synthesis was carried out by using conventional (C) or microwave (MW) heating upon convenience.…”

Gas-phase synthesis of 3-carboethoxy-quinolin-4-ones. A comprehensive computational mechanistic study to uncover the dark side of the Gould–Jacobs reaction

“…These precursors were satisfactory synthesized from anilines (1a-f) and diethylethoxymethylenmalonate (2) applying microwave irradiation as it was previously reported (step 1, Scheme 1). 15 As a rst attempt, malonate 3c was selected to optimize FVP conditions. Thus, pyrolysis were carried out at 250-500 C (increasing 50 C in each reaction) and $1 Â 10 À2 Torr, during 1 hour.…”

“…Although the G-J reaction has been widely used as a successful synthetic approach in solution 15 and also under solvent-free conditions, 16 this complex multi-step reaction has never been studied in detail in the gas phase. There are only a few reports of application of this reaction under ow systems 17,18 and similar cyclization under ash vacuum systems.…”

Recent advances in the synthesis of pharmaceutically active 4-quinolone and its analogues: a review

“…16 Similarly, an efficient microwave-assisted procedure for the synthesis of ethylquinolone-4-one-3-carboxylates 21 from p-substituted aniline 19 and diethyl-ethoxymethylenemalonate 20 in the presence of diphenyl ether at 80 °C under MW irradiation was reported by Malvacio and coworkers (Scheme 6). 17 Further, the quinolone obtained aer hydrolysis under MW irradiation furnished the corresponding quinolone-4-one-3-carboxylic acids 22 in very good to excellent yields. The advantage of this procedure is that it works for a wide substrate scope, and this route offers the benets of a very short reaction time and relatively good yield.…”