Catalytic Synthesis of Pyrazoles and Diazepines Under Green Conditions at Room Temperature Using Heteropolyacids Catalysts

Abstract

The catalytic performance of Preyssler, H₁₄[NaP₅W₃₀O₁₁₀]: Wells–Dawson, H₆[P₂W₁₈O₆₂]; and Keggin, H₃[PW₁₂O₄₀] and H₄[PMo₁₁VO₄₀], heteropolyacids as pure compounds have been studied in the synthesis of pyrazoles and diazepines in the condensation of hydrazines, hydrazides, and diamines with various 1,3-diketones. In all cases the best yields were obtained using H₁₄[NaP₅W₃₀O₁₁₀].

GRAPHICAL ABSTRACT

Keywords:

• Catalyst
• diazepine
• 1,3-diketone
• heteropolyacid
• pyrazole

ACKNOWLEDGMENTS

The authors are thankful to the Agricultural Researches and Services Center, Mashhad, Feyzabad, Iran; Mashhad Islamic Azad University and Chemistry Department, University of Oslo, Norway and National Research Council Canada for support of this work.

Notes

^a Yields are analyzed by GC.

^b The reactions are carried out in water as solvent and at room temperature.

^a Yields are analyzed by GC.

^b The reactions are carried out in water as solvent and at room temperature.

^a Yields are analyzed by GC.

^b The reactions are carried out in water as solvent and at room temperature.

^a Yields are analyzed by GC.

^b The reactions are carried out in water as solvent and at room temperature.

^a Isolated yields.

^a Isolated yields.

^a Isolated yields.

^a Isolated yields.

^{a , b} Isolated yields and yields obtained in the first, second, third, fourth and fifth reuse of the catalyst.

^a Yield of 3,5-dimethyl-1-phenyl-1H-pyrazole.

^b Yield of 2,4-dimethyl-3H-1,5-benzodiazepine.