A Modified Synthesis of Some Novel Polycyclic Aromatic Phenazines and Quinoxalines by Using the Tungstate Sulfuric Acid (TSA) as a Reusable Catalyst under Solvent‐free Conditions

Considering the synthesis of new compounds, we developed heterocyclic chemistry. We also helped to improve the classical synthetic route for the synthesis of quinoxalines and phenazines through implement in terms of solvent‐free reaction. For the condensation of 1,2‐dicarbonyls and o‐phenylenediamines under solvent‐free conditions at room temperature, tungstate sulfuric acid (TSA) was found to be an efficient and reusable reagent. The high yield of the pure products and simple preparation of the catalyst have allowed the synthesis of several phenazines and quinoxalines using this methodology.     

Efficient One-Pot Synthesis of Polyhydroquinoline Derivatives Using Silica Sulfuric Acid as a Heterogeneous and Reusable Catalyst Under Conventional Heating and Energy-Saving Microwave Irradiation

An efficient Hantzsch four-component condensation reaction for the synthesis of polyhydroquinoline derivatives was reported under two conditions: solvent-free conventional heating and energy-saving microwave irradiation. The process is simple and environmentally benign, and the use of a heterogeneous and reusable catalyst, high yields, and short reaction times are the key features of this protocol.     

Vanadatesulfuric Acid: A Novel,Recyclable, and Heterogeneous Catalyst for the One-Pot Synthesis of Dihydropyrimidinones and Dihydropyrimidinthiones Under Solvent-Free Conditions

Abstract

Vanadatesulfuric acid (VSA), as a novel and heterogeneous catalyst, was used for an efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones (thiones) using an aldehyde, urea, or thiourea and an acyclic β-dicarbonyl compound under solvent-free conditions. VSA is prepared via the reaction of sodium metavanadate and chlorosulfonic acid in high purity. The catalyst was characterized by FTIR, X-ray diffraction (XRD), and transmission electron microscopy (TEM) analysis. Compared to the classical Biginelli reactions, this method consistently has the advantage of high yields, simple workup, short reaction times, and reusability of the catalyst.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

以磷酸二氢铵为催化剂一锅法合成 3,4-二氢嘧啶-2-酮(英文)

A one-pot three component Biginelli condensation of different substituted aromatic and aliphatic aldehydes with ethyl acetoacetate and urea to the respective 3,4-dihydropyrimidin-2-( 1H)-ones under sol...     

One-Pot and Solvent-Free Synthesis of 1,4-Dihydropyridines and 3,4-Dihydropyrimidine-2-ones Using New Synthetic Recyclable Catalyst via Biginelli and Hantzsch Reactions

Pyridine dicarboxylic acid guanidine–cobalt complex (PDAG-Co) (3) catalyzes one-pot, three-component coupling of aldehydes, β-dicarbonyl compounds, and ammonium acetate to afford the corresponding 1,4-dihydropyridines (1,4-DHPs) via Hantzsch reaction. 3,4-Dihydropyrimidine-2-ones (3,4-DHPMs) and their sulfur analogs are also synthesized under the same conditions via Biginelli condensation protocol. The catalyst is reusable at least five times, highly efficient, easily prepared, and used under mild reaction conditions.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view free supplemental file.     

((3-(3-硅胶丙基)硫基)丙基)硫酸酯作为可回收催化剂用于合成4,4'-芳亚甲基-双(1H-吡唑-5-醇)(英文)

Sulfuric acid ([3-(3-silicapropyl)sulfanyl]propyl)ester is employed as a recyclable catalyst for the condensation reaction between aromatic aldehydes and 3-methyl-l-phenyl-5-pyrazolone. This condensation reaction was performed in ethanol under refluxing conditions giving 4,4'-alkylmethylene-bis(3-methyl-5-pyrazolones) in 74-90% yields. The heterogeneous catalyst was recycled and used in eleven runs for the reaction between benzaldehyde and 3-methyl-l-phenyl-5-pyrazolone without losing catalytic activity.     

二氧化硅负载磷钨酸催化合成3,4-二氢嘧啶-2(1H)-酮衍生物

以取代苯甲醛、乙酰乙酸乙酯和尿素为原料,以溶胶凝胶法制备二氧化硅负载的磷钨酸（H3PW12O40/SiO2）为催化剂,催化合成3,4-二氢嘧啶-2(1H)-酮,考察了三组分摩尔比、反应温度、催化剂用量及反应时间对反应收率的影响。 研究表明,H3PW12O40/SiO2是合成3,4-二氢嘧啶-2(1H)-酮的良性催化剂,在取代苯甲醛的用量为0.04 mol,反应温度为90 ℃的条件下,收率可达73.1%~88.4%。 催化剂和产品结构分别经IR、XRD、SEM和1H NMR、IR、MS等技术手段表征。     

Xanthan Sulfuric Acid: A New and Efficient Biosupported Solid Acid Catalyst for the Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones

Xanthan sulfuric acid (XSA) is employed as a recyclable catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones. These syntheses were performed via a one-pot, three-component condensation of aldehydes, amines, and urea/thiourea under solvent-free conditions.     

Cellulose Sulfuric Acid: An Efficient Biodegradable and Recyclable Solid Acid Catalyst for the Synthesis of 1-Oxo-hexahydroxanthene

A series of 1-oxo-hexahydroxanthene derivatives was synthesized at room temperature in solid state from substituted salicylaldehydes and substituted 1,3-hexanediones in the presence of a catalytic amount of cellulose sulfuric acid. The results showed that the reaction performed under solid-state conditions was benign to the environment, with higher yields and more convenient workup.

Silica Sulfuric Acid as an Inexpensive and Recyclable Solid Acid Catalyzed Efficient Synthesis of Quinolines

Summary. Silica sulfuric acid as an inexpensive and recyclable solid acid efficiently catalyzes the Fridedl?nder synthesis of quinolines through a condensation reaction of a 2-aminoaryl ketone with an activated α-CH acid compound under solvent-free conditions in high yields at 100°C.     

Expeditious Pechmann Condensation by Using Biodegradable Cellulose Sulfuric Acid as a Solid Acid Catalyst

A facile synthesis of coumarins was performed in excellent yields via Pechmann condensation by using different type of phenols and ethylacetoacetates under solvent–free media using both conventional method and microwave irradiation in short reaction times is described. The reaction workup is very simple, and the catalyst can be easily separated from the reaction mixture and reused several times in subsequent reactions.     

Silica Sulfuric Acid (SSA)/Polyethylene Glycol (PEG) as a Recyclable System for the Synthesis of Quinoxalines and Pyrazines

An efficient and facile method has been developed for the condensation of 1,2-diamines with α-hydroxyketones in polyethylene glycol (PEG) to quinoxalines and pyrazines with good yields in the presence of silica sulfuric acid (SSA). The important features of the methodology are simple operations, environmentally friendliness, and no requirement for metal catalysts. Additionally, the catalyst system (SSA/PEG) could be recovered easily and reused.     

Borax: An Ecofriendly and Efficient Catalyst for One-Pot Synthesis of 3,4-Dihydropyrimidine-2(1H)-ones under Solvent-Free Conditions

Borax in the presence of a very small amount of 5 M sulfuric acid efficiently catalyses the three-component condensation of an aldehyde, β-ketoester, and urea or thiourea to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones or 3,4-dihydropyrimidin-2(1H)-thiones in good to excellent yields under solvent-free conditions at 80 °C. Compared with the classical Biginelli reaction conditions, this new method has the advantage of excellent yield, short reaction time (1–2 h), easy workup, and no use of volatile organic solvent.     

Silica Sulfuric Acid: An Efficient,Reusable, Heterogeneous Catalyst for the One-Pot,Five-Component Synthesis of Highly Functionalized Piperidine Derivatives

A series of highly functionalized piperidine derivatives was synthesized through one-pot, five-component reaction of aldehydes, amines, and β-ketoesters. Silica sulfuric acid efficiently catalyzes the reaction to afford the corresponding piperidine derivatives in good yields. As a representative example, heating of 4-methylaninle, 4-fluorobezaldehyde, and methyl-acetoacetate in methanol in the presence of silica sulfuric acid furnished the corresponding ethyl 2,6-bis(4-fluorophenyl)-1-p-tolyl-4-(p-tolylamino)-1,2,5,6-tetrahydropyridine-3-carboxylate in excellent yield (85%). Most of the synthesized compounds were screened in vitro for their antibacterial and antifungal activities. Most of compounds showed significant antibacterial activity.     

Synthesis of gem-Dihydroperoxides from Ketones and Aldehydes Using Silica Sulfuric Acid as Heterogeneous Reusable Catalyst

Silica sulfuric acid (SSA) was found to efficiently catalyze the conversion of aldehydes and ketones directly into the corresponding gem-dihydroperoxides (DHPs) on treatment with aqueous 30% H₂O₂ at room temperature. Mild reaction conditions, good to excellent yields, short reaction times, low environmental impact, and recyclability of the catalyst are the main advantages of this synthetic method.     

硅胶硫酸:一种在温和及无溶剂条件下一锅法合成1,4-二氢吡啶的高效多相催化剂(英文)

A series of 1,4-dihydropyridines have been prepared by a one-pot condensation of aldehydes,ethyl acetoacetate,and ammonium acetate in the presence of a heterogeneous catalyst silica sulfuric acid at room temperature under solvent-free condition. This new protocol has the advantage of short reaction time and excellent yields,and is an environmentally benign route to the synthesis of 1,4-dihydropyridines.     

Polymer-Supported 4-Aminoformoyldiphenylammonium Triflate (PS-AFDPAT): An Effective and Recyclable Catalyst for the Biginelli Reaction

Polymer-supported 4-aminoformoyldiphenylammonium triflate (PS-AFDPAT) was used as an effective catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) via the Biginelli reaction. This immobilized catalyst could be easily recovered by simple filtration and recycled for 10 runs without significant decrease of the catalytic activity.     

One-Pot Syntheses of 3,4-Dihydropyrimidine-2(1H)-thiones Catalyzed by La(OTf)_3

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Cellulose Sulfuric Acid: Novel and Efficient Biodegradable and Recyclable Acid Catalyst for the Solid-State Synthesis of Thiadiazolo Benzimidazoles

An efficient method for the synthesis of 2-substituted benzimidazoles has been developed. In this method, benzo[c][1,2,5]thiadiazole-4,5-diamine was condensed with different aldehydes in the presence of cellulose sulfuric acid under solvent-free conditions by simple physical grinding of reactants using a mortar and pestle at room temperature. The methodology is mild, high-yielding, and green, and the catalyst could be easily recycled.     

A Simple and Convenient One-Pot Synthesis of Benzimidazole Derivatives Using Cobalt(II) Chloride Hexahydrate as Catalyst

A simple and efficient method for the convenient synthesis of 2-arylbenzimidazole has been described on reaction with o-phenylenediamine and various aromatic aldehydes using cobalt(II) chloride hexahydrate as a catalyst. The method is cost-effective, high-yielding, clean, and selective.