Table 2.

Synthesis of (a) 3-methyl-1,4-diphenyl-1,8-dihydro-5H-pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidine-5,7(6H)-dione derivatives, (b) 3-Methyl-4-phenyl-1,4,8,9-tetrahydro-5H-pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidine-5,7(6H)-dione derivatives, (c) Bis and tris 3-methyl-1,4-diphenyl-1,8-dihydro-5H-pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidine-5,7(6H)-dione derivatives using Fe₃O₄@Co(BDC)-NH₂ under ultrasonic irradiation.