Efficient Pseudo-Six-Component Synthesis of Tetrahydro-pyrazolopyridines Using [Zn-۲BSMP]Cl۲

Zn-[۲-boromophenyl-salicylaldimine-methylpyranopyrazole]Cl۲ {[Zn-۲BSMP]Cl۲}, 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 ۸۰ °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.