La_2O_3/TFE: An efficient system for room temperature synthesis of Hantzsch polyhydroquinolines

Lanthanum oxide（La2O3） in combination with 2,2,2-trifluoroethanol（TFE） was found to be an efficient system for the one-pot, four-component synthesis of Hantzsch polyhydroquinoline derivatives from aromatic aldehydes, dimedone, ethyl acetoacetate and ammonium acetate at ambient temperature. The catalyst is heterogeneous and reusable, hence can be separated easily and reused. The present method is featured by mild reaction conditions, use of heterogeneous catalyst, non-chromatographic purification,short reaction time and high yields, which make it an attractive route for the synthesis of polyhydroquinolines.

Microwave assisted synthesis of novel Hantzsch 1,4-dihydropyridines,acridine-1,8-diones and polyhydroquinolines bearing the tetrazolo[1,5-α]quinoline moiety and their antimicrobial activity assess

Microwave assisted efficient Hantzsch reaction via four-component coupling reactions of tetrazolo[1,5-α]quinoline-4-carbal-dehyde, dimedone/cyclohexane-1,3-dione,ethyl/methyl acetoacetate and ammonium acetate was described as the preparation of tetrazolo[1,5-α]quinoline based 1,4-dihydropyridines,acridine-1,8-diones and polyhydroquinolines.The process presented here is simple,rapid,environmentally welcoming and high yielding.All the derivatives were subjected to an in vitro antimicrobial screening against a representative panel of bacteria and fungi and results worth further investigations.

The SBA-15/SO_3H nanoreactor as a highly efficient and reusable catalyst for diketene-based,four-component synthesis of polyhydroquinolines and dihydropyridines under neat conditions

An efficient diketene ring-opening synthesis of polyhydroquinoline derivatives using SBA-15 sulfonic acid modified mesoporous substrates a green and reusable catalyst in a single-pot four-component coupling reaction of diketene,alcohol,enamine,and aldehydes is reported.Dihydropyridine derivatives based on neat adduct of diketene,alcohols and aldehydes using SBA-15/SO_3H nanoreactor as catalyst via a four-component reactions are also synthesized.The advantages of the present method include the use of a small amount catalyst,simple procedure with an easy filterable work-up,waste-free,green and direct synthetic method with an excellent yield of products with efficient use of catalyst and a short reaction time.

四丁基铵钨多酸[TBA]2[W6O19]:无溶剂条件下通过不对称汉斯反应快速合成聚氢化喹啉的新型可重复使用的非均相催化剂(英文)

A novel, efficient, and environmentally friendly method for the synthesis of polyhydroquinoline derivatives by a one‐pot, four‐component unsymmetrical Hantzsch condensation of dimedone, aldehydes, ethyl acetoacetate, and ammonium acetate in the presence of a catalytic amount of tetrabutylammonium hexatungstate [TBA]2[W6O19] under solvent‐free conditions has been developed. The results showed that this heterogeneous catalyst has high catalytic activity and the desired products were obtained in good to high yields. Moreover, the catalyst was found to be reusable and considerable catalytic activity was still achieved after the fifth run.

Cerium(Ⅳ) ammonium nitrate catalysed facile and efficient synthesis of polyhydroquinoline derivatives through Hantzsch multicomponent condensation

A general and convenient practical approach for the synthesis of polyhydroquinoline derivatives has been achieved via one-pot four-component Hantzsch condensation of aromatic aldehydes, dimedone, ethyl acetoacetate and ammonium acetate in the presence of a catalytic amount of cerium（IV） ammonium nitrate （CAN）, in ethanol solvent at ambient temperature. Simple work-up, mild reaction conditions, inexpensive and non-toxic catalyst, and excellent product yields are the advantageous features of this method.

二氧化钛纳米粒子催化合成Hantzsch酯和多氢喹啉衍生物(英文)

1,4-Dihydropyridine and polyhydroquinoline derivatives have been prepared efficiently in a one-pot synthesis via Hantzsch condensation using nanosized titanium dioxide as a heterogeneous catalyst.The present methodology offers several advantages such as excellent yields,short reaction times (30-120 min),environmentally benign,and mild reaction conditions.The catalyst can be readily separated from the reaction products and recovered in excellent purity for direct reuse.

二氧化锡纳米粒子催化四组分Hantzsch缩合合成多氢喹啉衍生物(英文)

Tin dioxide (SnO2 ) nanoparticles efficiently catalyzed unsymmetrical four-component Hantzsch condensations of various aldehydes, dimedone, ethyl acetoacetate, and ammonium acetate to form polyhydroquinoline derivatives in excellent yields. This novel method offers several advantages over the traditional method of synthesizing these compounds, including safety, mild conditions, short reaction times, high yields, and an easy workup.

One-step,synthesis of Hantzsch esters and polyhydroquinoline derivatives using new organocatalyst

Herein we report an efficient organocatalyst for the multicomponent Hantzsch reaction under mild condition.The product easily isolated by simple filtration and catalyst can be recovered.

PPA-SiO_2 catalyzed efficient synthesis of polyhydroquinoline derivatives through Hantzsch multicomponent condensation under solvent-free conditions

Silica gel-supported polyphosphoric acid （PPA-SiO2） was found to be an efficient catalyst for the one-pot four-component Hantzsch condensation reaction of aryl aldehydes, dimedone, ethyl acetoacetate and ammonium acetate to afford the corresponding polyhydroquinoline derivatives in high yields. The main advantages of the present approach are short reaction times, clean reaction profiles, simple experimental and workup procedures.

MgO Nanoparticles as a Recyclable Heterogeneous Catalyst for the Synthesis of Polyhydroquinoline Derivatives under Solvent Free Conditions

Magnesium oxide nanopartticels in average size between 35--120 nm were prepared by sonochemistry method. Synthesis of polyhydroquinoline derivatives using MgO nanoparticles from the reaction of dimedone, benzaldehyde ethyl acetoacetate and ammonium acetate under solvent-free conditions is reported. Easy handling, reusability, thermal stability and non-toxicity of the catalyst make the present protocol as an eco-friendly and economically acceptable method for synthesis of these heterocycles.