1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU): as a highly efficient bicyclic amidine catalyst promoted solvent-free and one-pot synthesis of 1H-pyrazolo [1, 2-b] phthalazine-5,10-dione derivatives

1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) as a highly efficient bicyclic amidine catalyst promoted one-pot multi-component synthesis of biologically active 1H-pyrazolo [1, 2-b] phthalazine-5, 10-dione derivatives via one-pot four-component condensation reaction of phthalimide, hydrazine monohydrate, aryl aldehydes and malononitrile under solvent-free conditions through simple filter with no necessity of chromatographic purification steps. Use of safe, non-volatile, non-corrosive, highly efficient, readily available and easy to handle of catalyst, one-pot reaction, high yields and short reaction times, economical and convenient synthesis, solvent-free conditions and operational simplicity are among the other added advantages that make this approach an attractive alternative for the synthesis of these biologically active compounds.