Catalytic Synthesis of Fused 1,4-Dihydropyridines and 1,4-Dihydropyridine Derivatives Using Preyssler Heteropolyacids Catalyst

Abstract

An efficient and convenient method for the synthesis of 1,4-dihydropyridines from β-dicarbonyl compounds, aldehydes, and ammonium acetate and the synthesis of fused 1,4-dihydropyridines from dimedone in the presence of Preyssler heteropolyacid catalyst are reported under reflux conditions with good to excellent yields. Preyssler heteropolyacid catalyst is easily prepared, stable (up to 300 °C), reusable, efficient, green and inexpensive.

GRAPHICAL ABSTRACT

Keywords:

• 1,4-Dihydropyridines
• dimedone
• Hantzsch reaction
• heteropolyacid
• Preyssler

ACKNOWLEDGMENTS

The authors are thankful to the Agricultural Researches and Services Center, Mashhad, Feyzabad, Iran; Mashhad Islamic Azad University; Chemistry Department, University of Oslo, Norway; and National Research Council Canada for support of this work. Special thanks go to J. (Hans) W. Scheeren from the Organic Chemistry Department, Radboud University, Nijmegen, the Netherlands.

Notes

^a Isolated yields.^{[ 13 ]}

^b All the products were identified by spectroscopic analysis (IR, ¹H NMR, ¹³C NMR).

^c Yields obtained in the first, second, and third use of the catalyst.

^d The control reaction was carried out on the aldehydes 2a and 2d in refluxing water without the Preyssler heteropolyacid catalyst.

^a Isolated yields.^{[ 14 ]}

^b All the products were Identified by spectroscopic analysis (IR, ¹H NMR, ¹³C NMR).

^c Yields obtained in the first, second, and third use of the catalyst.

^d The control reaction was carried out on the aldehydes 4a and 4g in refluxing water without the Preyssler heteropolyacid catalyst.