A series of pyrano[3,2-c]quinolone derivatives
has been synthesized in the presence of taurine (2-aminoethanesulfonic
acid) as a green bio-organic catalyst and water as the solvent. The
target compounds were synthesized through the three-component reaction
between aldehydes, malononitrile/ethylcyanoacetate, and 4-hydroxy-1-methyl-2(1H)-quinolone. The advantages of this protocol are excellent
yields of products, short reaction times, cost efficiency, atom economy,
and a simple work-up procedure with no need for extra purification
techniques. Moreover, the catalyst can be easily recovered and reused
for up to three cycles without losing any significant activity.