New and General Nitrogen Heterocycle Synthesis: Use of Heteropoly Acids as a Heterogeneous Recyclable Catalyst

Abstract

An efficient synthetic method of six- and five-member nitrogen heterocyclic compounds was developed. Nitrogen heterocyclic compounds were prepared by condensation of the β-dicarbonyl compounds with the corresponding β- or γ-amino alcohols, subsequent cyclization, and spontaneous aromatization in the presence of a catalytic amount of Keggin-type heteropoly acids under very mild conditions.

Keywords:

• Amino alcohols
• bifunctional (acid and redox) catalyst
• β-dicarbonyl compounds
• Keggin-type heteropoly acid

ACKNOWLEDGMENT

The authors are thankful to Alzahra Research Council for the partial financial support.

Notes

^a In all entries, 0.01 mmol H₃PW₁₂O₄₀ was added to the reaction solution.

^a Reaction conditions: Keggin-type heteropoly acids (0.01 mmol), 1,3-dicarbonyl compound (1 mmol), amino alcohol (1.5 mmol), solvent-free system, rt, 6 h.

^a Reaction conditions: Keggin-type heteropoly acids (0.01 mmol), 1,3-dicarbonyl compound (1 mmol), amino alcohol (1.5 mmol), solvent-free system, rt, 6 h.

^b Yields analyzed by gas chromatography.

Notes. Reaction conditions: Keggin-type heteropoly acids (0.01 mmol), 1,3-dicarbonyl compound (1 mmol), amino alcohol (1.5 mmol), solvent-free system, rt, 6 h.

^a Yields were analyzed by gas chromatography.