Efficient Pseudo-Six-Component Synthesis of Tetrahydro-pyrazolopyridines Using [Zn-2BSMP]Cl2

Zn-[2-boromophenyl-salicylaldimine-methylpyranopyrazole]Cl2 {[Zn-2BSMP]Cl2}, as a Schiff base complex, efficiently catalyzed the pseudo-six-component synthesis of tetrahydrodipyrazolopyridines by the condensation reaction of aryl aldehyde, hydrazine hydrate, ethyl acetoacetate and urea at 80 °C. Urea was used instead of ammonium salts as a source of ammonia by in situ generation of ammonia, in the presence of a little amount of water.