Synthesis of benzimidazoles/benzothiazoles by using recyclable,magnetically separable nano-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> in aqueous medium

An efficient, simple, ecofriendly and cost-effective method has been developed for the synthesis of benzimidazole/benzothiazole derivatives by a two-component reaction, involving 1,2-diamino benzene/2-amino thiophenol and substituted aromatic aldehydes using recyclable nano-Fe₂O₃ catalyst (10 mol%) in water afforded with excellent yields (75–85%). The most important feature of this protocol is short reaction times, high yields, aqueous reaction medium, efficient recycling and high stability of the catalyst.     

Highly efficient synthesis of dicoumarols and xanthene derivatives in presence of Brønsted–Lewis acidic ionic liquids catalyst

A series of metal chloride-based acidic ionic liquids have been prepared and used as an efficient catalyst in one-pot multicomponent synthesis of biscoumarins and substituted xanthenes derivatives under solvent-free conditions. Among the acidic ionic liquids, N-methylpyrrolidonium zinc chloride (Hnmp/ZnCl₃)-based Brønsted–Lewis acidic ionic liquids were found to be an effective and recyclable catalyst for a one-pot synthesis of biscoumarins through the domino Knoevenagel–Michael reaction of a variety of aldehydes with 4-hydroxycoumarin in short reaction times. The reactions which occur under relatively mild conditions afforded the biscoumarin derivatives employing a very low loading of catalyst in satisfactory isolated yields and high purity after simple work-up. The Brønsted–Lewis acidic ionic liquid catalyst was reused four times without any variation in yield.     

Synthesis of some novel 2‐substituted‐N‐aryl‐benzoxazole‐5‐carboxamides using cobalt dipyridine dichloride as a catalyst

An efficient synthesis of some novel 2‐substituted‐N‐aryl‐benzoxazole‐5‐carboxamides from 2‐substituted — 5‐carbomethoxy benzoxazole on treatment with different substituted anilines promoted by cobalt dipyridine dichloride as a catalyst is described. This new approach has the advantage of excellent yields (90%) and short reaction times 1‐2 h.     

A green route for the synthesis of 2-substituted benzoxazole derivatives catalyzed by Al-exchanged K10 clay

A new, simple, and efficient protocol is developed for the synthesis of 2-substituted benzoxazole derivatives through N–C–O bond formation using Al³⁺-exchanged K10 clay (Al³⁺-K10) as catalyst. A wide range of benzoxazole derivatives are synthesized in high yields without affecting many functional groups. Hot filtration experiments showed the absence of metal leaching and catalyst can be reused for five times with only a slight decrease in yield.     

Hybrid crystal NH3(CH2)4NH3SiF6 as an efficient catalyst for the synthesis of benzoxazoles,benzimidazoles and benzothiazoles under solvent-free conditions

An easy synthetic protocol for the synthesis of biologically active benzimidazole, benzothiazole and benzoxazole derivatives has been demonstrated using a hybrid crystal NH₃(CH₂)₄NH₃SiF₆ as a mild and efficient heterogeneous catalyst. Short reaction times, solvent-free conditions, good to excellent yields, easy reusability and use of an eco-friendly catalyst are some of the significant attributes of the present method.     

Zirconium triflate: An efficient catalyst for the synthesis of quinolines and quinoxalines

An environmentally friendly method is described for the preparation of substituted quinoline and quinoxaline derivatives using Zr(OTf)₄ as an efficient catalyst. The method is based on using 1,3-diketones, ketones and 2-aminoaryl ketones under solvent-free conditions and also on using 1,2-diketone, 1,2-diamine in EtOH/H₂O at room temperature for quinloine and quinoxaline synthesis, respectively. The advantages in using this method, include its environmental friendliness, simple operating process and good yields.     

Phospho sulfonic acid as efficient heterogeneous Brønsted acidic catalyst for one-pot synthesis of 14<Emphasis Type="Italic">H</Emphasis>-dibenzo[<Emphasis Type="Italic">a,j</Emphasis>]xanthenes and 1,8-dioxo-octahydro-xanthenes

A simple, efficient procedure for the preparation of phospho sulfonic acid PO(OSO₃H)₃ as a Brønsted acidic and recoverable heterogeneous catalyst is described, used for the one-pot synthesis of aryl-14H-dibenzo[a,j]xanthenes and 1,8-dioxo-octahydro-xanthenes. A cost-effective, simple and convenient procedure for the synthesis of aryl-14H-dibenzo[a,j]xanthenes was developed via a one-pot condensation from substituted benzaldehydes and β-naphthol under solvent-free conditions. The one-pot condensation of substituted benzaldehydes and 5,5-dimethyl-1,3-cyclohexanedione (dimedone) under solvent-free conditions leads to 1,8-dioxo-octahydro-xanthenes. These protocols afford a number of advantages, such as: excellent yields, very short reaction times, easy procedure, simple methodology and ease of preparation and regeneration of the catalyst.     

KF/Al2O3 Mediated Multicomponent Reactions for the Efficient Synthesis of Highly Substituted Dihydropyridines

KF/Al₂O₃ was found to be an efficient solid supported catalyst for the facile access of highly substituted dihydropyridine derivatives from the multicomponent reaction of aromatic aldehydes, amines, malononitrile, and alkylacetylenedicarboxylates. The notable advantages of this protocol are reusable catalyst, good yields, applicable to a wide range of substrates for the synthesis of pharmacologically interesting dihydropyridine derivatives.     

Lithium bromide as an efficient,green, and inexpensive catalyst for the synthesis of quinoxaline derivatives at room temperature

Abstract

An efficient, simple, and green procedure for the synthesis of quinoxaline derivatives is described. The condensation of 1,2-diamines with 1,2-diketones using lithium bromide (LiBr) in H₂O/EtOH as a green reaction media at room temperature affords the title compounds in high to excellent yields and in short reaction times.     

A Simple,Mild and Efficient One‐Pot Synthesis of 2‐Substituted Benzimidazoles in the Presence of H2O2/HCl under Microwave Irradiation

A simple, fast and efficient method for the preparation of several 2‐substituted benzimidazole derivatives is reported. Compounds were synthesized through a rapid one‐pot synthesis via microwave irradiation, starting from aldehydes and o‐phenylenediamine, in the presence of H₂O₂/HCl system in acetonitrile. The significant features of this method are short reaction times, high yields, easy and quick isolation of the products.     

Selectfluor promoted environmental-friendly synthesis of 2H-chromen-2-ones derivatives under various reaction conditions

A simple, clean and benign route to the synthesis of 2H-chromen-2-ones derivatives through one-pot condensation of ??-ketoesters and substituted phenols in the presence of 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bistetrafluoroborateis (Selectfluor? F-TEDA-BF₄) as catalyst under solvent free reaction conditions was experimented. The application of ultrasonic irradiation improved the yields and reduced the reaction times. The use of selectfluor catalyst is feasible because of its stability, commercial value, easy handling, easy recovery and good activity. To extend our research, the ability of selectfluor for the synthesis of 2-aminochromene derivatives was also examined.     

Palladium(II) Immobilized Onto the Glucose Functionalized Magnetic Nanoparticle as a New and Efficient Catalyst for the One‐pot Synthesis of Benzoxazoles

Palladium(II) have been immobilized into the nano magnetic Fe₃O₄ which was functionalized with glucose in order to achieve a one‐pot synthesis of 2‐substituted benzoxazole derivatives with high yields in the diverse range of organic solvents. The nano catalyst is highly dispersive in polar solvents and can be easily recovered and reused for 6 runs without significant loss of its activity. Finally, the catalyst was fully characterized by FT‐IR, TGA, CHN, SEM, EDX and atomic absorption spectroscopy.     

One-Pot Synthesis of 2,4,5-Trisubstituted Imidazoles Using MoO3/SiO2, an Efficient and Recyclable Catalyst

A simple one-pot synthesis has been developed for the synthesis of 2,4,5-trisubstituted imidazoles using an efficient and recyclable MoO₃/SiO₂ solid acid catalyst by condensation of benzil or benzoin, benzaldehyde, and ammonium acetate in acetonitrile as a solvent. Using this solid catalyst, the reactions could be carried out under mild reaction conditions with very good yield of imidazoles, up to 95%. This catalyst could be recycled very easily, which makes this methodology environmentally benign.     

Poly(vinylpyrrolidonium) perchlorate catalyzed one-pot synthesis of tricyclic dihydropyrimidine derivatives

A simple and efficient procedure for the synthesis of benzo[4,5]imidazo[1,2-α]pyrimidine and 2-amino-4-substituted-1,4-dihydrobenzo[4,5]imidazolo[1,2-α]pyrimidine-3-carbonitrile derivatives using poly(vinylpyrrolidonium) perchlorate {[PVPH]ClO₄} as a newly reported, modified polymeric catalyst is reported. Some of the advantages of this novel synthetic method are: easy preparation of the catalyst, simple and easy work-up procedure, short reaction times, high to excellent yields of the products and reusability of the catalyst.     

Design,Synthesis, In Vitro Antimicrobial,Antioxidant Evaluation,and Molecular Docking Study of Novel Benzimidazole and Benzoxazole Derivatives

A series of novel 2‐substituted benzimidazole and benzoxazole derivatives as a potential antimicrobial and antioxidant agent were synthesized via coupling of N‐methyl‐o‐phenylenediamine or 2‐amino‐phenol with aromatic aldehyde and acid in the presence of polyphosphoric acid as an efficient catalyst as well as solvent by conventional method in short reaction times with excellent yield. The newly synthesized benzimidazole and benzoxazole derivatives were evaluated for antimicrobial and antioxidant activity and exhibited excellent to good activities compared to the standard drugs. Furthermore, the theoretical predictions based on molecular docking against microbial DNA gyrase could provide an insight into the plausible mechanism of action and establish a link between the observed antimicrobial activity and the binding affinity shedding light on specific thermodynamic (bonded and nonbonded) interactions governing the activity. Furthermore, the synthesized compounds were analyzed for absorption, distribution, metabolism, and excretion properties and exhibited potential properties to build up as good oral drug candidates.     

Eco‐friendly synthesis of 3,4‐dihydroquinoxalin‐2‐amine,diazepine‐tetrazole and benzodiazepine‐2‐carboxamide derivatives with the aid of MCM‐48/H5PW10V2O40

A heterogeneous material composed of MCM‐48/H₅PW₁₀V₂O₄₀ was produced and used as an efficient, eco‐friendly and highly recyclable catalyst for the one‐pot and multicomponent synthesis of 3,4‐dihydroquinoxalin‐2‐amine, diazepine‐tetrazole and benzodiazepine‐2‐carboxamide derivatives in aqueous media and at room temperature with high yields in short reaction times (40–60 min). The recoverable catalyst was easily recycled at least five times without any loss of catalytic activity. The structures of obtained products were confirmed using ¹H NMR and ¹³C NMR spectra.     

室温下Cu掺杂的ZnO纳米粉末催化多组分一锅法合成完全取代的茚并[1,2-b]吡啶(英文)

Cu doped ZnO nanocrystalline powder(10 mol%) has been found to be an efficient catalyst for the one‐pot multi‐component synthesis of fully substituted new indeno[1,2‐b]pyridines through a com-bination of 1,3‐indandione, propiophenone or acetophenone derivatives, aromatic aldehydes, and ammonium acetate in ethanol/H2 O at room temperature. The methodology is mild, efficient and high to excellent yielding.     

Facile One‐pot Synthesis of Substituted Dihydropyrrol‐2‐ones via Four‐component Domino Reaction of Amines,Dialkyl Acetylenedicarboxylates and Formaldehyde

A mild and efficient method for the one‐pot synthesis of substituted dihydropyrrol‐2‐one derivatives is described via four‐component domino reaction of amines, dialkyl acetylenedicarboxyaltes and formaldehyde in the presence of 1‐methyl‐2‐oxopyrrolidinium hydrogen sulfate ([Hpyro][HSO₄]) as ionic liquid catalyst. This facile approach proceeded smoothly in good to high yields and pure products are separated from the reaction mixture by simple filtration.     

Silica Phosphoric Acid (SPA) as a Highly Active,Reusable, Heterogeneous Catalyst for the Synthesis of 2-Amino/Anilino-5-ARYL-1,3,4-Thiadiazine Bromide Derivatives

Silica phosphoric acid has been found to be an efficient catalyst for the synthesis of 2-amino/anilino-5-aryl-1,3,4-thiadiazine bromide derivatives from the reaction of thiosemicarbazide and α-bromoketones in acetonitrile at room temperature. The catalyst can be reused for four times without any significant loss of catalytic activity. The experimental procedure is simple, and the products are obtained in high yield.     

Microwave assisted one pot synthesis of 2-ethylamino benzimidazole,benzoxazole and benzothiazole derivatives

A rapid and efficient one-pot method for the synthesis of 2-ethylamino benzimidazole, benzoxazole, and benzothiazole derivatives has been described. The reaction of o-phenylenediamines or o-aminophenols or 2-mercaptoanilines with EDC.HCl under microwave irradiation afforded the corresponding 2-ethylamino benzimidazole, benzoxazole and benzothiazole derivatives in excellent yields.