Search

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]. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]