nahso4 –sio2 promoted solvent-free synthesis of triazolo [1,2 -a]indazole-triones

a new one-pot, efficient three-component condensation of dimedone, urazole and aromatic aldehydes in the presence of silica supported sodium hydrogen sulfate as an effective heterogeneous catalyst for the synthesis of novel triazolo[1,2 -a]indazole-1,3,8 -trione derivatives under solvent-free conditions is described.