A Nano-sized Nd–Ag@polyoxometalate Catalyst for Catalyzing the Multicomponent Hantzsch and Biginelli Reactions

Manizheh Ghanbarian,Masoud Mirzaei,Seyeed Yahya Shirazi Beheshtiha,Nahid Lotfian,Majid M Heravi,Vahideh Zadsirjan

doi:10.1007/s10876-019-01739-w

Abstract

For the first time the catalytic activity of AgNdSiW11, was examined in two named reactions, namely Hantzsch and Biginelli reactions. A simple, eco-friendly and highly efficient one-pot synthesis of polyhydroquinoline derivatives via Hantzsch multicomponent reactions (MCRs) involving cyclocondensation of differently-substituted aldehydes, β-ketoesters or dimedone, active methylene compounds, and ammonium acetate as a source of nitrogen, in the presence of AgNdSiW11 as a catalyst in EtOH/H2O under reflux conditions in high yields was successfully achieved. Furthermore, the catalytic performance of AgNdSiW11 was also successfully tested in the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones via Biginelli MCR involving cyclocondensation of differently-substituted aldehydes, ethyl acetoacetate and urea as source of nitrogen in the presence of AgNdSiW11 under reflux conditions in EtOH/H2O. This prolific combination of Ln and POMs inaugurates a powerful class of catalysts for the different chemical transformations, which overcomes key limitations of previously established salts and Lewis acidic metals-based catalysts under low catalyst loading, the use of water scavengers, dry solvents and additives for facilitating the specialized experimental setups commonly employed to the organic reactions.

Highlights

The application of efficient, easy to recover, reusable and eco-friendly catalysts to comply with the principles of green chemistry is a key priority for synthetic organic chemists [1]
Based on the points mentioned above and in continuation of our interest in exploring green heterogeneous catalysts for organic transformations leading to the heterocyclic systems, we report our successful attempt to apply AgNdSiW11 as an efficient and reusable catalyst in the synthesis of polyhydroquinoline derivatives via the Hantzsch reaction (Scheme 1) and dihydropyrimidones via the Biginelli reaction (Scheme 2)
In continuation of our above-mentioned interest in the catalyzed synthesis of heterocyclic compounds [64] via multicomponent reactions (MCRs) [60] using HPAs and their polyoxometalates as efficient catalysts [65] under green conditions [66], in this research, we tried to extend our research activities, focusing our attention to examine the catalytic activity of a virgin heteropoly acid, AgNdSiW11 in the synthesis of a

Summary

Introduction

The application of efficient, easy to recover, reusable and eco-friendly catalysts to comply with the principles of green chemistry is a key priority for synthetic organic chemists [1]. A simple, eco-friendly and highly efficient one-pot synthesis of polyhydroquinoline derivatives via Hantzsch multicomponent reactions (MCRs) involving cyclocondensation of differently-substituted aldehydes, b-ketoesters or dimedone, active methylene compounds, and ammonium acetate as a source of nitrogen, in the presence of AgNdSiW11 as a catalyst in EtOH/H2O under reflux conditions in high yields was successfully achieved.

Results

Conclusion