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
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.[ Citation 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.[ Citation 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.