Synthesis Of Trisubstituted Imidazoles Research Articles

Synthesis of Trisubstituted Imidazoles by Sulfonated Magnetic Cellulose-Nanoparticles

Key words imidazoles - nanoparticles - acid catalysis - diketones - aldehydes

Fly Ash Catalyzed Microwave Assisted Multicomponent Synthesis of Trisubstituted Imidazole Derivatives

Background: Imidazoles are important class of heterocyclic compounds showing biological activities. Several methods have been investigated till today for the synthesis of triaryl imidazoles. Some of these classical as well as nonclassical methods experiences drawbacks for instance elongated reaction time, expensive catalyst, low yield of product etc. Hence improvement of a competent method is still necessary. This paper reveals greener protocol for the synthesis of triaryl imidazoles by cyclocondensation of aromatic aldehydes, benzil and ammonium acetate in existence of fly ash as an efficient heterogeneous catalyst by means of microwaves. Methods: Heterogeneous catalyst fly ash was prepared by simple thermal activation method. The catalyst was systematically characterized through wet chemical analysis, XRD, FT-IR, SEM and EDS. The structural analysis was done using XRD and IR. Morphological study was performed using SEM and elemental composition studied by EDS technique. This activated fly ash catalyst was applied in the synthesis of trisubstituted imidazoles. The progress of reaction was checked by TLC and the synthesized compounds were further confirmed by FT-IR, 1H-NMR and 13C-NMR spectroscopy. Results: To check feasibility of activated fly ash for trisubstituted imidazole synthesis, reactions under microwave irradiation employed. The products were obtained in higher yield (92-98%). Conclusion: The fly ash was found to be highly effective in the synthesis of trisubstituted imidazoles under microwave irradiation. The significant features of this protocol are rate enhancement, uncomplicated work up process, high yields and employ of ecofriendly catalyst. Keywords: Wet chemical analysis, microwave, fly ash, heterogeneous, catalyst, imidazole.

Citrate trisulfonic acid: A heterogeneous organocatalyst for the synthesis of highly substituted Imidazoles

Citrate trisulfonic acid (CTSA), as a novel recyclable and eco‐benign organocatalyst, was employed for the efficient and one‐pot synthesis of trisubstituted imidazoles and tetrasubstituted imidazoles using aldehydes, ammonium acetate or aniline, and benzoin, benzyl, or 9,10‐phenanthrenequinone under solvent‐free conditions providing high to excellent yields. CTSA is easily prepared via the reaction of trisodium citrate and chlorosulfonic acid in high purity. Compared to the conventional procedures, the present method offers several advantages, including high yields, easy work‐up, short reaction time, reusability of the catalyst, and simple purification of the products.

Tungstophosphoric acid supported on core-shell polystyrene-silica microspheres or hollow silica spheres catalyzed trisubstituted imidazole synthesis by multicomponent reaction

Materials based on tungstophosphoric acid supported on core-shell polystyrene-silica microspheres or hollow silica spheres were prepared, characterized and used as catalysts in the synthesis of trisubstituted imidazoles by a multicomponent reaction under solvent-free conditions.For the preparation of the two different silica-based structures, silica was synthesized using tetraethylorthosilicate (TEOS) as precursor in an ethanol-ammonium solution and polystyrene spheres as template or core. The formation and growth of the silica layer to obtain the core-shell microspheres were followed by 24h. Then, the hollow spheres were obtained by calcination of the core-shell material at 500°C for 3h. Both supports were impregnated with tungstophosphoric acid (TPA) solutions.A smooth appearance of the spheres was observed by scanning electron microscopy (SEM). Mesoporous materials were obtained, without important microporosity, as determined from N2 adsorption-desorption isotherms. The Fourier transform infrared (FT-IR) spectra confirmed that complete removal of the polystyrene core can directly be achieved by calcination at 500°C, and also that Keggin undegraded TPA species are present in the impregnated solids. The acidic characteristics of the solids were evaluated by potentiometric titration, showing that they exhibit very strong acid sites. Moreover, peaks assigned to crystalline forms of TPA were observed by XRD.The yields obtained in the solvent-free synthesis of 2,4,5-triphenyl-1H-imidazole and other eight trisubstituted imidazoles were high, without formation of by-products resulting from competitive reactions or decomposition products, so the prepared materials are highly selective catalysts.

ChemInform Abstract: Graphene Oxide—Chitosan Bionanocomposite: A Highly Efficient Nanocatalyst for the One‐Pot Three‐Component Synthesis of Trisubstituted Imidazoles under Solvent‐Free Conditions.

AbstractImidazoles (III) are rapidly, conveniently, and eco‐friendly obtained by reaction of benzil (I) or benzoin with various aromatic aldehydes and ammonium acetate.

Synthesis of trisubstituted imidazoles via a convergent reaction network from methyl ketones and benzoins

A novel method for constructing trisubstituted imidazoles has been created using simple and readily available aromatic ketones, benzoins, and ammonium acetate as starting materials. The new synthetic strategy utilized a convergent integration of two self-labor domino sequences, providing a typical example for logical self-organization synthesis.

Simple and efficient synthesis of trisubstituted imidazoles

The thermally activated or microwave-induced one-pot three-component condensation of arylglyoxal hydrates, 1,3-dimethylbarbituric acid, and guanidine salts or methylisothiuronium hydroiodide gave respectively 2-amino-5-aryl- and 5-aryl-2-methylsulfanylimidazoles containing a 1,3-dimethylbarbituric acid residue. An unexpected course for the condensation was discovered in the case of guanidine hydrochloride, leading to 5-(2-aryl-2-oxoethyl)-1,3-dimethylbarbituric acids. 2-Amino-2-arylimidazoles under the conditions of such three-component condensation formed Michael adducts involving 5-(2-aryl-2- oxoethylidene)-1,3-dimethylbarbituric acids and the C-5 atom of the imidazole ring.

Synthesis of Trisubstituted Imidazoles via Oxidative Diamination of Alkynes

Key words imidazoles - copper catalysis - oxidative deamination - alkynes

ChemInform Abstract: Highly Efficient One‐Pot Synthesis of Trisubstituted Imidazoles under Catalyst‐Free Conditions.

AbstractThis is the first report for a catalyst‐free and very mild synthesis of imidazoles, which are generated from readily available starting materials in a facile and atom economical three‐component procedure.

Ionic liquid [EMIM]OAc under ultrasonic irradiation towards the first synthesis of trisubstituted imidazoles

The ionic liquid 1-ethyl-3-methylimidazole acetate ([EMIM]OAc) was found to be a mild and effective catalyst for the efficient, one-pot, three-component synthesis of 2-aryl-4,5-diphenyl imidazoles at room temperature under ultrasonic irradiation. This procedure has many obvious advantages compared to those reported in the previous literatures, including avoiding the use of harmful catalysts, reacting at room temperature, high yields, simplicity of the methodology.

Multicomponent Synthesis of Trisubstituted Imidazoles

Multicomponent Synthesis of Trisubstituted Imidazoles

ChemInform Abstract: Tandem Oxidation Process Using Ceric Ammonium Nitrate: Three‐Component Synthesis of Trisubstituted Imidazoles under Aerobic Oxidation Conditions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Tandem Oxidation Process Using Ceric Ammonium Nitrate: Three-Component Synthesis of Trisubstituted Imidazoles Under Aerobic Oxidation Conditions

By combining a ceric ammonium nitrate (CAN)–catalyzed aerobic oxidation of α-hydroxy ketones with a subsequent three-component condensation reaction using aldehydes and ammonium acetate, highly substituted imidazole derivatives can be assembled. This reaction is an important approach for the synthesis of highly substituted imidazole derivatives and was carried out in good to excellent yields in ethanol as an environmentally benign solvent.

1,1,3,3‐N,N,N′,N′‐Tetramethylguanidinium Trifluoroacetate Ionic Liquid Promoted Efficient One‐Pot Synthesis of Trisubstituted Imidazoles.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

1,1,3,3‐N,N,N′,N′‐Tetramethylguanidinium Trifluoroacetate Ionic Liquid–Promoted Efficient One‐Pot Synthesis of Trisubstituted Imidazoles

Trisubstituted imidazoles have been synthesized in very short reaction times with excellent yields in the presence of 1,1,3,3‐N,N,N′,N′‐tetramethylguanidinium trifluoroacetate as an ionic liquid at 100°C. The ionic liquid can be recycled for subsequent reactions without any appreciable loss of efficiency.

Synthesis of Trisubstituted Imidazoles by Palladium‐Catalyzed Cyclization of O‐Pentafluorobenzoylamidoximes: Application to Amino Acid Mimetics with a C‐Terminal Imidazole.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of Trisubstituted Imidazoles by Palladium-Catalyzed Cyclization of O-Pentafluorobenzoylamidoximes: Application to Amino Acid Mimetics with a C-Terminal Imidazole

1-Benzyl-4-methylimidazoles with a range of substituents at the 2-position are prepared from O-pentafluorobenzoylamidoximes on treatment with catalytic amounts of Pd(PPh3)4 and triethylamine. The sequence provides access to optically active amino acid mimetics with a C-terminal imidazole. [structure: see text]

Microwave‐Assisted One‐Pot Synthesis of Trisubstituted Imidazoles on Solid Support.

AbstractFor Abstract see ChemInform Abstract in Full Text.