A convenient four-component synthesis of 6-amino-4-alkyl/aryl-3-methyl-2,4-dihydropyrano[2,3- c]pyrazole-5-carbonitriles.They are widely used for industrial purposes and also exhibit a broad range of antimicrobial activity. They are synthesized by using ethylacetoacetate, hydrazine hydrate, malononitrile, and various aldehydes using Tetra n-butyl ammonium bromide (TBAB) as a catalyst and water as solvent under mild reaction conditions. This method has several advantages such as high yield, mild reaction condition, operational simplicity, easy work-up procedure with environment friendly nature.