NH₄Cl/Zn powder: An efficient, chemoselective reducing catalyst for the microwave‐assisted synthesis of 2,3‐disubstituted quinolines via tandem Knoevenagel condensation

Abstract

An efficient, a hitherto unreported, sustainable, and environmentally friendly microwave‐assisted synthesis of 2,3‐disubstituted quinolines by reductive cyclization of 2‐nitrobenzaldehydes and various active methylene compounds via tandem Knoevenagel condensation promoted by an efficient eco‐friendly, chemoselective reducing catalyst ammonium chloride (NH4Cl) and zinc powder was developed. This present methodology is a mild, green, efficient, and environmentally benign process as it eliminates the harsh reaction conditions, non‐volatile solvents, relatively expensive reagents, high catalyst loading, and also provides a number of other benefits like fast synthesis, simple reaction set‐up, and good to the excellent yield of the products.

Synthesis, antimicrobial evaluation, and molecular modelling studies of Niclosamide derivatives as biotin carboxylase inhibitors.

“…A solution of Niclosamide 1 in diethyl ether was refluxed with K2CO3 to afford Niclosamide potassium salt 2 and without separation was refluxed with solution of thiophene-2-carbonyl chloride 3a, isonicotinoyl chloride 3b or 4-(1H-indol-3-yl)butanoyl chloride 3c in acetone for 7 hours 26 to yield the target prodrugs 4-6; respectively (Scheme 1).…”