Showing papers in "Journal of Heterocyclic Chemistry in 2008"

An Efficient synthesis of pyrimido[4,5-b]quinoline and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidine derivatives via multicomponent reactions in ionic liquid

Abstract: A series of pyrimido[4,5-b]quinoline and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidine derivatives were synthesized via the three-component reaction of an aldehyde, 6-aminopyrimidine-2,4-dione and 5,5-dimethyl-1,3-cyclohexanedione or 1,3-indanedione in ionic liquid 1-n-butyl-3-methylimidazolium bromide ([bmim]Br). This protocol has the advantages of easier work-up, milder reaction conditions, high yields and an environmentally benign procedure compared with other methods.

An efficient synthesis of polyhydroacridine derivatives by the three-component reaction of aldehydes, amines and dimedone in ionic liquid

Abstract: In this paper the preparation of 3,3,6,6-tetramethyl-9,10-diaryl-1,2,3,4,5,6,7,8,9,10-decahydroacridine-1,8-dione derivatives from aldehydes, aromatic amines and 5,5-dimethyl-1,3-cyclohexanedione in 1-n-butyl-3-methylimidazolium bromide ([bmim]Br) is described. The structures of these compounds were characterized by elemental analysis, IR and 1H NMR spectra and further confirmed by single crystal X-ray diffraction analysis.

Chemistry and application of 4-oxo-4H-1-benzopyran-3-carboxaldehyde

Abstract: The Chemistry and application of the title aldehyde and some simple derivatives thereof are reviewed.

Synthesis of 3-substituted indoles promoted by pulverization-activation method catalyzed by Bi(NO3)3·5H2O

Abstract: A new, facile, efficient, “green” and chemoselective procedure for the synthesis of indole derivatives has been developed with pulverization-activation method catalyzed by Bi(NO3)3·5H2O (PAMC- Bi(NO3)3·5H2O) through grinding of indoles with aldehydes or Michael acceptors in the presence of catalytic amounts of Bi(NO3)3·5H2O under solvent-free conditions.

Kinetic study of meso‐tetraphenylporphyrin synthesis under microwave irradiation

Abstract: A typical synthesis of meso-tetraphenylporphyrin was carried out from condensation of pyrrole with benzaldehyde in acidic medium under microwave irradiation. A batch of tests were carried out and a systematic evaluation of organic acid, reactant concentration, microwave power, time of reaction, presence of added oxidant at normal pressure conditions and in closed vessels system, allowed us to find a good set of conditions within the range of study. The best result was achieved in only 5 minutes of irradiation showing a great reduction in reaction time and reaching yields higher than those mentioned in literature for the synthesis under classical synthetic heating method.

Synthesis of some novel pyrazolo[1,5‐a]pyrimidine, 1,2,4‐triazolo[1,5‐a]pyrimidine, pyrido[2,3‐d]pyrimidine, pyrazolo[5,1‐c]‐1,2,4‐triazine and 1,2,4‐triazolo[5,1‐c]‐1,2,4‐triazine derivatives incorporating a thiazolo[3,2‐a]benzimidazole moiety

Abstract: E-3-(N,N-Dimethylamino)-1-(3-methylthiazolo[3,2-a]benzimidazol-2-yl)prop-2-en-1-one (2) was synthesized by the reaction of 1-(3-methylthiazolo[3,2-a]benzimidazol-2-yl)ethanone (1) with dimethylformamide-dimethylacetal. The reaction of 2 with 5-amino-3-phenyl-1H-pyrazole (4a) or 3-amino-1,2,4-(1H)-triazole (4b) furnished pyrazolo[1,5-a]pyrimidine and 1,2,4-triazolo[1,5-a]pyrimidine derivatives 6a and 6b, while the reaction of enaminone 2 with 6-aminopyrimidine derivatives 7a,b afforded pyrido[2,3-d]pyrimidine derivatives 9a,b, respectively. The diazonium salts 11a or 11b coupled with compound 2 to yield the pyrazolo[5,1-c]-1,2,4-triazine and 1,2,4-triazolo[5,1-c]-1,2,4-triazine derivatives 13a and 13b. Some of the newly synthesized compounds exhibited a moderate effect against some bacterial and fungal species.

Solvent‐free synthesis of 5‐methyl‐7‐aryl‐4,7‐dihydrotetrazolo[1,5‐a]pyrimidine‐6‐carboxylic esters catalyzed by sulfamic acid

Abstract: The solvent-free synthesis of 5-methyl-7-aryl-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylic esters was performed and effectively catalyzed by sulfamic acid. Compared with conventional methods, this protocol features mild reaction conditions and high yields. Furthermore, it is solvent-free and thus eco-friendly.

The synthesis and fluorescence of novel N-substituted-1,8-naphthylimides

Abstract: The synthesis and characterisation of a series of novel 4-acylamino and 4-alkylamino-N-1,8-naphthalimides is described. The UV-visible absorption and emission properties of the compounds are reported. Significant solvent effects are noted for 4-n-butyl-9-n-butyl-1,8-naphthylimide. The incorporation of acetyl and chloroacetyl groups into the 4-substituent markedly increases the fluorescence quantum yield compared with 4-alkylamino substituemnts.

Simple and mild procedures for synthesis of benzimidazole derivatives using heterogeneous catalyst systems

Abstract: TsOH/graphite and N,N-dimethylaniline/graphite were found to be catalyst systems for condensation reaction of o-phenylendiamine with different aldehydes to form benzimidazole derivatives under mild and simple conditions. The graphite was easily recovered by a simple extraction and could be reused without decrease of activity in the presence of fresh TsOH and N,N-dimethylaniline.

An efficient synthesis of 5-benzoyloxazolines by regio- and stereo-controlled reaction of N-substituted 2-benzoylaziridines under microwave irradiation

Abstract: Several N-acyl-2-benzoylaziridines were prepared conveniently in good to high yields (71-93%) and used in the preparation of 5-benzoyloxazolines (76-91%) by a regio- and stereo-controlled reaction in the presence of Nal as an efficient catalyst under microwave irradiation in short reaction times (5-10 mins). The structure of the regioisomeric product was confirmed by X-ray analysis.

An efficient synthesis of quinoxaline derivatives mediated by stannous chloride

Abstract: Various biologically important quinoxaline derivatives were efficiently synthesized in excellent yields by the reaction of 1,2-diketones and 2-nitroaniline, benzofuroxan or 1,2-dinitrobenzene promoted by SnCl22H2O. The role of stannous chloride is acting as both reductive agent and catalyst in this synthesis. This new method has the advantages of accessible starting materials, convenient manipulation, short reaction time and high yields.

Synthesis of azirines containing aldehyde functionality and their utilization as synthetic tools for five membered oxazoles and isoxazoles

Abstract: A simple and useful procedure for the synthesis of azirines containing aldehyde functionality from open chain bromo/chloro-aldehydes at room temperature is reported. The scope of the ring expansion reaction of a number of 3-substituted-2-formyl-azirines has been examined using different oraganometallic catalysts and a variety of Lewis acids.

Reaction of β-dimethylaminovinyl ketones with hydroxylamine: A simple and useful method for synthesis of 3- and 5-substituted isoxazoles

Abstract: The regioselective synthesis of 3- and 5-substituted-isoxazoles from the reaction of β-dimethyl-aminovinyl ketones [R-C(O)CHCH-NMe2, where R Ph, MeO-4-C6H4, F-4-C6H4, Cl-4-C6H4, Br-4-C6H4, O2N-4-C6H4, fur-2-yl, thien-2-yl, pyrrol-2-yl, Et and CCl3] and hydroxylamine hydrochloride varying only the reaction conditions (with and without the addition of pyridine) is reported.

Progress in the chemistry of 4‐ thiazolidinones

Abstract: This review article includes a recent development in the chemistry of 4-thiazolidinones. Structure, basicity, synthetic aspects, reactions, and applications were also reported.

Studies with enaminonitriles: Synthesis and chemical reactivity of 2-phenyl-3-piperidin-1-yl acrylonitrile under microwave heating

Abstract: Benzyl cyanide reacts with triethylorthoformate and piperidine in DMF solution to yield the title compound 2. This reacted with aromatic amines to yield either aminoacrylonitriles or quinoline depending on reaction conditions and substitution pattern on the aromatic amine. The reaction of compound 2 with hydrazine hydrate could only be effected in the microwave oven and resulted in the formation of aminopyrazole 7. Diazotization of 7 and coupling with an active methylene reagent afforded pyrazolo[5,1-c]-[1,2,4]triazine derivatives.

Synthesis and biological evaluation of novel methylene‐bisthiazolidinone derivatives as potential nematicidal agents

Abstract: In a one pot procedure, a series of novel methylene-bis-thiazolidinone derivatives 5 and 6 was prepared by condensation of 5-(3-formyl-4-methoxybenzyl)-2-methoxybenzaldehyde 3 with mercapto acids and primary aromatic amines 4 in presence of ZnCl2 under both microwave irradiation and conventional heating conditions. High yields are achieved even on a gram scale, while reaction times are considerably shortened under microwave irradiation compared to conventional heating conditions. Characterization of new compounds has been done by means of IR, NMR, MS and elemental analysis. The nematicidal and antibacterial activity of the compounds has also been evaluated.

Polystyrene‐supported AICI3: A highly active and reusable heterogeneous catalyst for the one‐pot synthesis of dihydropyrimidinones

Abstract: An environmentally benign Biginelli protocol for the one-pot synthesis of substituted 3,4-dihydropyrimidin-2(1H)-ones using polystyrene supported aluminium chloride as catalyst has been achieved. This polymeric catalyst is stable and can be easily recovered and reused without obvious change in their efficiency.

A new, efficient and chemoselective one-pot protocol for synthesis of 4-arylidene-2-phenyl-5(4H)-oxazolones from aryl aldehyde bisulfite adducts promoted by POCL3

Abstract: A one-pot procedure for the synthesis of 4-arylidene-2-phenyl-5(4H)oxazolones directly from aryl aldehyde bisulfite adducts in the absence of Ac2O in good to excellent yields using phosphoryl chloride is reported. In addition, the observed chemoselectivity can be considered as a noteworthy advantage of this method.

Synthesis of 3‐aminoalkyl‐2‐arylaminoquiazolin‐4(3H)‐ones and 3,3′‐disubstituted bis‐2‐arylaminoquinazolin‐4(3H)‐ones via reactions of 1‐aryl‐3‐(2‐ethoxycarbonylphenyl)carbodiimides with diamines

Abstract: 1-Aryl-3-(2-ethoxycarbonylphenyl)carbodiimides 2, obtained from aza-Wittig reactions of iminophosphorane 1 with aryl isocyanates, reacted with primary diamines in 1:1 and 2:1 molar ratio under mild conditions to give selectively the regioisomers 3-aminoalkyl-2-arylaminoquinazolin-4(3H)-ones 3 and 3,3′-disubstituted bis-2-arylaminoquinazolin-4(3H)-ones 4 in good yields, respectively. To fully characterize the regioselectivity of aza-Wittig reactions of 1-aryl-3-(2-ethoxycarbonylphenyl)carbo-diimides with primary diamines, crystals of 4e were obtained, and its structure was determined by X-ray crystallography.

Synthesis of α-[5-(5-amino-1,3,4-thiadiazol-2-yl)-2-imidazolylthio]acetic acids

Abstract: The paper describes synthesis and antituberculosis activity of α-[5-(5-amino-1,3,4-thiadiazol-2-yl)-imidazol-2-ylthio]acetic acids (5a,b). The compounds were tested against Mycobacterium tuberculosis strain H37Rv in comparison to rifampicin. Compounds exhibited low activity (MIC ≤ 6.25 μg/ml, % inhibition ≥ 24).

Synthesis of C‐pivot lariat ethers

Abstract: This review covers the main strategies for the synthesis of N-pivot lariat ethers as well as their specific syntheses.

Synthesis of novel pyrazolo[3,4‐d]pyridazine, pyrido[1,2‐a]benzimidazole, pyrimido[1,2‐a]benzimidazole and triazolo[4,3‐a]pyrimidine derivatives

Abstract: 4-Acetyl-5-methyl-1-phenyl-1H-pyrazole reacts with dimethylformamide dimethylacetal (DMF-DMA) to afford the corresponding (E)1-(5-methyl-1-phenyl-1H-pyrazol-4-yl)-3-(N,N-dimethylamino)-2-propen-1-one. The latter product undergoes regioselective 1,3-dipolar cycloaddition with nitrilimines and nitrile oxides to afford the novel 3-aroyl-4-(5-methyl-1-phenyl-1H-pyrazol-4-yl)carbonyl-1-phenylpyrazole and 3-aroyl-4-(5-methyl-1-phenyl-1H-pyrazol-4-yl)carbonyl isoxazole derivatives, respectively. It reacts also with 1H-benzimidazole-2-acetonitrile, 2-aminobenzimidazole and 3-amino-1,2,4-triazole to afford the novel pyrido[1,2-a]benzimidazole, pyrimido[1,2-a]benzimidazole and the triazolo[4,3-a]pyrimidine derivatives, respectively. The reaction of 3-aroyl-4-(5-methyl-1-phenyl-1H-pyrazol-4-yl) carbonyl-1-phenylpyrazole derivatives with hydrazine hydrate led to a new pyrazolo[3,4-d]pyridazine derivatives.

Synthesis, Spectroscopic and Antibacterial Investigations of New Hydroxy Ethers and Heterocyclic Coumarin Derivatives

Abstract: The reactions between oligoethylene glycol diglycidyl ethers 2a-c with both 7-hydroxy-4-methyl-2H-chromen-2-one and 4-hydroxy-2H-chromen-2-one lead to new hydroxy ethers 3 and 4 containing coumarin moieties in good yield. The synthesis of 3-(3-(dimethylamino)acryloyl)-4-hydroxy-2H-chromen-2-one 5 and new heterocyclic compounds 4-hydroxy-3-(1H-pyrazol-3-yl)-2H-chromen-2-one 6a, 4-hydroxy-3-(1-phenylpyrazol-3-yl)-2H-chromen-2-one 6b and 4-hydroxy-3-(isoxazol-3-yl)-2H-chromen-2-one 6c is also described. All compounds were characterized by 1H NMR, 13C{1H} NMR, 2D-1H-13C HMBC, 2D-1H NOESY NMR, IR, and MS spectroscopy. Additionally, the antibacterial activity of the new products containing coumarin moiety was evaluated. This activity is clearly dependent on the chemical structure of compounds.

Microwave-assisted Döbner Synthesis of 2-Phenylquinoline-4-carboxylic Acids and their Antiparasitic Activities

Abstract: A series of twelve substituted 2-phenylquinoline-4-carboxylic acids analogous to antimalarial and antileishmanial natural products was developed via the Dobner reaction employing microwave irradiation (MW). The products were obtained in moderate yields in 0.5-3 minutes and nine of them were evaluated in vitro against the parasites responsible for malaria, leishmaniasis and trypanosomiasis diseases (WHO, Switzerland). Four compounds exhibited activity against Trypanosoma cruzi and another two resulted active against Plasmodium falciparum and Leishmania infantum, respectively.

N-Alkylation of imides using phase transfer catalysts under solvent-free conditions

Abstract: N-Alkylation of imides in the reaction of imides and alkylhalides, catalyzed by PT catalysts under solvent-free conditions, has been developed. The reaction occurs in the presence of K2CO3, and in many cases it takes place spontaneously. In the N-benzylation reaction, it has been recognized that TBAB (tetrabutylammonium bromide) and TBATFB (tetrabutylammonium tetrafluoroborate) show highest catalytic effect. Versatility and synthetic capacity of the solvent-free alkylation has been confirmed by N-benzylation and N-ethylation of various imides. The developed procedure gives easy access to N-(ω-bromoalkyl)imides.

Synthesis of substituted amino-cycloalkyl[b]thieno-[3,2-e]pyridines

Abstract: An efficient two respectively three steps procedure for the synthesis of cycloalkyl[b]thieno[3,2-e]-pyridine amines was developed and in general good to very good yields were obtained.

Sulfonic acid functionalized silica as an efficient heterogeneous recyclable catalyst for one-pot synthesis of 2-substituted benziimidazoles

Abstract: An efficient one-pot synthesis of 2-substituted benzimidazoles from o-phenylenediamine and aldehydes in the presence of sulfonic acid functionalized silica at room temperature is reported.

Phosphomolybdic acid catalyzed facile one‐pot synthesis of 2,4,5‐triaryl‐1H‐imidazoles from benzil and aromatic aldehydes

Abstract: A facile one-pot synthesis of 2,4,5-triaryl-1H-imidazoles with better yields and shorter reaction time from the condensation of benzil, ammonium acetate and aromatic aldehydes using the catalyst phosphomolybdic acid is described

Green and high efficient synthesis of triaza‐benzo[b]fluoren‐6‐one derivatives in water under microwave irradiation

Abstract: Triaza-benzo[b]fluoren-6-one derivatives were synthesized via the three-component reaction of aldehyde, cyclohexane-1,3-dione compound and 2-aminobenzimidazole in water under microwave irradiation. The new protocol has the advantages of excellent yield, low cost, reduced environment impact, wide scope and convenient procedure.

Palladium/tetraphosphine catalyzed suzuki cross‐coupling of heteroarylboronic acids with aryl halides

Abstract: cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/[PdCl(C3H5)]2 efficiently catalyses the Suzuki reaction of heteroarylboronic acids with aryl bromides and also the coupling of arylboronic acids with heteroaryl bromides. The coupling of thiophene- or benzothiopheneboronic acids, furan- or benzofuranboronic acids and 3-pyridineboronic acid with a variety of aryl bromides gave the corresponding coupling products in good yields. However, in most cases, better results in terms of ratio substrate/catalyst were obtained for the reverse reaction using heteroaryl bromides with arylboronic acids.