Abstract:Hantzsch reaction is classified as a one-pot, four-component process for the synthesis of 1,4-dihydropyridine and polyhydroquinoline derivatives. A green protocol for the promotion of the synthesis of polyhydroquinoline derivatives using polyethylene-glycol (PEG) as a green solvent in the absence of any catalysts under ultrasound irradiation at ambient temperature is demonstrated in this report. High to excellent yields, short reaction times, mild conditions, ambient temperature, inexpensive and availability of the substrates make this procedure an attractive methodology. Keywords: Hantzsch reaction; PEG; Catalyst-free; DHPs derivative, ultrasound irradiationIntroduction:

The three-component Willgerodt-Kindler reaction with was efficiently catalyzed by the Cu(I)@chitosan as a heterogeneous nano-bio catalyst to afford the corresponding thioamides in high to quantitative yields in short reaction times and mild conditions. The Cu(I)@chitosan can be recovered at least 4 times without significant loss of its catalytic activity. The reaction was carried out in the aqueous media.