Ionic liquid 1-butyl-3-methylimidazolium bromide: A green reaction media for the efficient synthesis of 3-methyl-1,4-diphenyl-1,4,5,7-tetrahydro-pyrazolo[3,4-d]pyrimidine-6-ones/thiones using phthalimide-N-sulfonic acid as catalyst

A simple, green and environmentally benign procedure was developed for the one pot synthesis of 3-methyl-1,4-diphenyl-1,4,5,7-tetrahydro-pyrazolo[3,4-d]pyrimidine-6-one/thiones using catalytic amount of phthalimide-N-sulfonic acid (PISA) in 1-butyl-3-methylimidazolium bromide ([Bmim][Br]) ionic liquid via the three-component reaction of 1-phenyl-3-methyl-1H-pyrazole-5(4H)-one, aromatic aldehyde and urea/thiourea. [Bmim][Br] as reaction media offers several advantages including non-toxic, non-corrosive, shorter reaction times, high yield of the products, mild reaction conditions as well as simple experimental and isolation procedures.