Cellulose sulfuric acid catalyzed multicomponent reaction for efficient synthesis of pyrimido and pyrazolo[4,5-b]quinolines under solvent-free conditions

Cellulose sulfuric acid was used as an efficient biopolymer-based catalyst for the synthesis of tetrahydropyrimido[4,5-b]quinoline-2,4,6-triones and hexahydro-2H-pyrazolo[5,4-b]quinoline-6-ones via three component reaction of aldehyde, 5,5-dimethyl-1,3-cyclohexadione and 6-amino-1,3-dimethyluracil or 5-amino-3-methyl-1-phenypyrazole under solvent-free conditions at 90 °C. The major advantages of the present method are simple experimentation, use of inexpensive and eco-friendly reusable catalyst with good yields and short reaction times.