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3-Cyano-2(1H)-pyridinethiones are of interest because of their use as intermediates for the synthesis of biologically active polycyclic compounds 1 2. Numerous thieno[2,3-b]pyridines have been inve...

An improved green Knoevenagel condensation of various aromatic aldehydes with 4-thiazolidinones in the presence of anhydrous ammonium acetate can be achieved by grinding at room temperature in the absence of solvents. This process is simple, efficient, economical, and environmentally benign compared to classical reactions.

An improved Claisen–Schmidt condensation reaction of methyl ketones and aromatic aldehydes can be achieved by grinding at room temperature in the absence of solvents. This process is simple, efficient, economical, and environmentally benign compared to classical reactions.

2,4-Dihydropyrazole glucosides 3a-3c were prepared and tested for their antitumor activity. The structures of these compounds were established by (1)H and (13)C-NMR spectroscopy. Glucoside 3b shows an in vitro IC(50) value of 16.4 muM against proliferation of the human promyelotic leukemia (HL60) cell line.

Thiazolylcyanothioacetanilides react with α-haloketones and haloesters to give the corresponding thiophene or thiazole derivatives according to the reaction conditions. Pyrazolo[1,5-a]pyrimidines and pyrazolo[5,1-c]triazines were synthesized by reaction of 3-amino-4-(4′-arylthiazol-2′-yl)-5-phenylaminopyrazole with different reagents. Structures of the new compounds were confirmed by elemental analyses, spectral data, and alternative methods of synthesis whenever possible. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 508–516, 1999

Hydrazonoyl chlorides 1 reacted with 2-aryl-1-cyano-1-thiazol-2-ylethenes 2 in presence of triethyl-amine to give the cycloadducts 4. which were converted to the corresponding pyrazoles 5 by the action of sodium methoxide. The reaction of hydrazonoyl halides 1 and 6 with each of 2-aryli-dene-2-cyanoethanethioamides 7 and 2-arylhydrazono-2-cyanoethanethioamides 14 in ethanolic tri-ethylamine or ethanolic sodium hydroxide solutions, has been investigated. Structures of all the products were established on the basis of their spectral data and alternative synthesis.

3-Ethoxycarbonyl-5-methyl-1-(4-methylphenyl)-4-pyrazoloylhydroximoyl chloride (1) reacted with o-phenylenediamine, o-aminothiophenol, o-aminophenol and methyl anthranilate to afford 3-nitrosoquinoxaline, benzothiadiazine, benzoxadiazine, and 3-hydroxyquinazoline, respectively. Imidazo[1,2-a]pyridine, imidazo[1,2-a]pyrimidine and isoxazole derivatives were obtained via the reaction of 1 with 2-aminopyridine, 2-aminopyrimidine and the appropriate active methylene compounds, respectively. Pyrazolo[3,4-d]pyridazines, and pyrrolidino[3,4-d]isoxazolines derivatives were also synthesized. The structures of the newly synthesized compounds were established on the basis of spectral data and alternate synthesis whenever possible.

Hydrazonoyl halides react with methyl arylmethylenehydrazinecarbodithioate in the presence of triethylamine to give 2,3-dihydro-1,3,4-thiadiazoles.

3-Phenyl-5-aminopyrazole (1) reacts with carbon disulfide, followed byin situ reaction with α-haloketones3a–c, to afford5,7a, and7b, respectively. Compounds5 and7 were further utilized for the formation of heterocycles and their fused derivatives.

The reaction of phenyl isothiocyanate and sulfur with the Knovenagel condensated adducts la-e afforded the pyridino[2,3-d]thiazole derivatives 3a-e. The latter compounds proved to be versatile starting materials for the synthesis of polyfunctionally substituted thiazolo[4′,5′:2,3]pyridino[4,3-d]pyridazine and thiazolo[4,5-b)isoquinoline derivatives. Chemical and spectroscopic evidence for the structures of the new compounds, along with a sequence leading to their formation is described.

A simple and efficient one-pot three-component synthesis of the title compounds (IV) is presented.

The reaction of phenyl isothiocyanate with the Knovenagel condensated active methylene compounds 1a-d gave the non-isolable salts 3a-d . The latter underwent in-situ heterocyclization on treatment with some halogenated compounds e.g. phenacyl bromide, ethyl bromoacetate δ-bromoacetoacetanilide, ethyl δ-bromoacetoacetate and δ-bromo-β-oxo-butyronitrile into the corresponding polyfunctionally substituted 3-(thiazol-2′-yliene)pyridine derivatives, which could also be annulated into fused heterocyclic ring systems. Chemical and spectroscopic evidences for the structure of the new compounds are described.

A series of trifluoromethyl-substituted hexahydropyrimidine derivatives were efficiently synthesized in excellent yields via one-pot three-component reaction of aromatic aldehydes, ethyl trifluoroacetoacetate and thiourea(urea) in presence of p-toluenesulfonic acid under solvent-free conditions at room temperature by grinding. The present method does not involve any hazardous organic solvent and has proven to be simple, efficient, environmentally benign and cost-effective compared with the classical synthetic methods. These compounds were screened for their antibacterial activities against Escherichia coli and Bacillus thuringiensis and found to exhibit remarkably better antibacterial activities than the control drug.

Facile syntheses of pyrazole, pyridine, pyrimidine and pyrazolo[3,4-d]pyrimidine derivatives have been achieved by the reaction of β-enamino nitrile 2a with hydrazines, phenyl isothiocyanate, thiourea and active methylene reagents. The β-enamino ketone 2e with the same reagents affords 3,5-dimethyl heterocyclic ring systems.

3-Phenylpyrazol-5-yl diazonium chloride (1a) was coupled with 2-aminocrotonitrile (4) to afford 4-phenyl-6-methylpyrazolo[5,1-c]-1,2,4-triazine-7-carbonitrile (5). Upon reaction with sulfur, compound 5 was transformed into 8-amino-4-phenylthieno[4,3-e]pyrazolo[5′,1-c']-1,2,4-triazine. Compound 6 underwent 4 + 2 cycloaddition with several dipolarophiles such as maleic anhydride, N-phenylmaleimide and acrylonitrile to afford a variety of new annelated pyrazolo[5,1-c]-1,2,4-triazine derivatives via hydrogen sulfide elimination. The structures of the newly synthesized compounds were determined by elemental analyses and spectral data. A sequence leading to the formation of these compounds and their reactions is described.

The reaction of phenyl isothiocyanate with the Knovenagel condensated active methylene compounds 1a-d gave the non-isolable salts 3a-d . The latter underwent in-situ heterocyclization on treatment with some halogenated compounds e.g. phenacyl bromide, ethyl bromoacetate δ-bromoacetoacetanilide, ethyl δ-bromoacetoacetate and δ-bromo-β-oxo-butyronitrile into the corresponding polyfunctionally substituted 3-(thiazol-2′-yliene)pyridine derivatives, which could also be annulated into fused heterocyclic ring systems. Chemical and spectroscopic evidences for the structure of the new compounds are described.

3-Amino-5-trifluoromethyl-1,2,4-triazole has been utilized for the syntheses of poly-substituted 2-trifluoromethyl-[1,2,4]triazolo[1,5-a] pyrimidine derivatives, via its reactions with acrylonitrile derivatives and various 1,3-dicarbonyl compounds, and of trifluoromethyl[1,2,4]triazolo[5,1-c]triazine derivatives, via its diazotization and coupling with active methylene reagents.

The reaction of 3-amino-5-trifluoromethyl[1,2,4]triazole with carbon disulfide or phenyl isothiocyanate followed by heterocyclization with haloketones, haloesters and hydrazonoyl halides has been utilized for the synthesis of the title compounds; chemical and spectroscopic evidence for the suggested structures of the new compounds and a sequence leading to their formation are discussed.

The reaction of C-(benzoyl)-N-(phenyl)formohydrazonoyl bromide with 1,1-dicyanothioacetanilide was reinvestigated. The product was elucidated on the basis of elemental analysis, spectral data and alternative synthesis. Also, reaction of hydrazonoyl halides with different thioanilides were investigated.

3-Phenylpyrazol-5-yl diazonium chloride (1a) was coupled with 2-aminocrotonitrile (4) to afford 4-phenyl-6-methylpyrazolo[5,1-c]-1,2,4-triazine-7-carbonitrile (5). Upon reaction with sulfur, compound 5 was transformed into 8-amino-4-phenylthieno[4,3-e]pyrazolo[5′,1-c']-1,2,4-triazine. Compound 6 underwent 4 + 2 cycloaddition with several dipolarophiles such as maleic anhydride, N-phenylmaleimide and acrylonitrile to afford a variety of new annelated pyrazolo[5,1-c]-1,2,4-triazine derivatives via hydrogen sulfide elimination. The structures of the newly synthesized compounds were determined by elemental analyses and spectral data. A sequence leading to the formation of these compounds and their reactions is described.

An improved Claisen–Schmidt condensation reaction of methyl ketones and aromatic aldehydes can be achieved by grinding at room temperature in the absence of solvents. This process is simple, efficient, economical, and environmentally benign compared to classical reactions.

Several new pyrrole and pyrazole derivatives were synthesised via the reactions of 4-cyano-2,3-diphenyl-2H-pyrrol- 5-thione.

2,3-Diphenyl-4-cyano-pyrrole-5-thione (4) was prepared either by the reaction of benzoin (1) and cyanothioacetamide (3) followed by cyclization using AcOH/sodium acetate or by refluxing a mixture of benzoin (1) and cyanothioacetamide in pyridine to afford directly4. Several new pyrrole and pyrazole derivatives were synthesised using4 as synthon. The structure of the newly synthesised derivatives were based on celemental and spectral data studies. Methylation of the SH group in4 afforded5. Reaction of4 with ethyl bromo acetate afforded (6). Treatment of (5) and (6) with hydrazine hydrate afforded the same pyrazole derivative (10) through the intermediate (9). Treatment of6 with aniline and phenylhydrazine afforded the pyrrole derivatives8a,b respectively. Treatment of6 while dil HCl gave 2,3-diphenyl-4-cyano-pyrrole-5-one (7). Treatment of6 with NH3/EtOH afforded the amidic derivatives (11) with treatment of6 with NH3/heat then acidification it gave the carboxylic derivatives (12).

A novel synthesis of 2-thio-, and 2-oxo- and 2-methoxy-3-cyano-pyridine derivatives utilizing 2-furyl-methylene- and 2-thienylmethylene derivatives of acetophenone and activated nitriles as startin...

To a solution of 4-(4-methylphenylazo)-5-trifluoromethyl-2,4-dihydropyrazol-3-one (1) [1] (0.81g, 3 mmol) in hexamethyldisilazine (HMDS) (25 ml) was added few crystals of anhydrous ammonium sulfate [2].[...]

A novel synthesis of 2-thio-, and 2-oxo- and 2-methoxy-3-cyano-pyridine derivatives utilizing 2-furyl-methylene- and 2-thienylmethylene derivatives of acetophenone and activated nitriles as startin...

The reaction of C-(benzoyl) -N- (phenyl) formohydrazonoyl bromide with 1,1-dicyanothioacetanilide was reinvestigated. The product was elucidated on the basis of elemental analysis, spectral data and alternative synthesis. Also, reaction of hydrazonoyl halides with different thioanilides were investigated.

Hydrazonoyl halides 1 and 6a–f reacted with methyl hydrazinecarbodithioate (2) and methyl 3-[1-(aryl)alkylmethylidene]hydrazinecarbodithioates (9a–d or 10a,b), in ethanolic triethylamine solution, to afford the corresponding 2-hydrazono-3,5-diphenyl-2,3-dihydro-1,3,4-thiadiazoles (3), 5-methyl-2-methylsulfanyl-6-phenylhydrazono-1,3,4-thiadiazine (8) and 2,3-dihydro-1,3,4-thiadiazoles 17–20a–f, respectively.

The reaction of 3-amino-5-trifluoromethyl[1,2,4]triazole with carbon disulfide or phenyl isothiocyanate followed by heterocyclization with haloketones, haloesters and hydrazonoyl halides has been utilized for the synthesis of the title compounds; chemical and spectroscopic evidence for the suggested structures of the new compounds and a sequence leading to their formation are discussed.

Unsymmetrical azines were obtained via the reaction of hydrazonoyl halides with methyl dithioate. Hydrazonoyl halides reacted with phenyldithiocarbamate and phenylthiourea to give 2-anilino-2,3-dihydro-1,3,4-thiadiazoles and 2-anilino-5-phenylazothiazoles depending on the hydrazonoyl halides used.

The desired compound 2 was obtained by complete deacetylation of compound 1 [1] using triethylamine [2].[...]

To a cold solution of 5-trifluoromethyl-2,4-dihydropyrazol-3-one [1,2] (0.76 g, 5 mmol) in ethanol (25 ml) containing sodium acetate (0.82 g, 10 mol), p-tolyldiazonium chloride [ca. 5 mmol; prepared by adding a solution of sodium nitrite (5 mmol / 2 ml H2O) to an ice cold solution of p-toluidine in 2 ml conc. HCl] was added dropwise with stirring at 0-5°C.[...]

The desired compound 2 was obtained by complete deprotection of the acetylated nucleoside 1 [1] using triethylamine [2].[...]

To a cold solution of 5-trifluoromethyl-2,4-dihydropyrazol-3-one [1,2] (0.76 g, 5 mmol) in ethanol (25 ml) containing sodium acetate (0.82 g, 10 mol), 3-nitrobenzenediazonium chloride ( 5 mmol) was added dropwise with stirring at 0-5°C.[...]

3-Amino-5-trifluoromethyl-1,2,4-triazole has been utilized for the syntheses of poly-substituted 2-trifluoromethyl-[1,2,4]triazolo[1,5-a] pyrimidine derivatives, via its reactions with acrylonitrile derivatives and various 1,3-dicarbonyl compounds, and of trifluoromethyl[1,2,4]triazolo[5,1-c]triazine derivatives, via its diazotization and coupling with active methylene reagents.

Some observations are made on the nature of the reactions involved in the conversion of aspen poplar into a variety of chemical products as a result of its interaction with carbon monoxide and water in the presence of sodium carbonate at elevated temperatures and pressures. The original carbon content of the wood is distributed between an oil phase, a complex mixture of highly oxygenated water-soluble products many of which have been identified as low molecular weight aliphatic alcohols, ketones, and acids, and a gaseous phase consisting of mainly hydrogen and carbon dioxide. Using model substances (cellulose, cellobiose, D-glucose, D-fructose, D-xylose, D-sorbitol, glycerol, and an isolated lignin) information was obtained on the origin of the oil and of the water-soluble products. Studies at temperatures from 160° to 360 °C revealed a marked exothermic reaction occurring in the 200–240 °C range for wood and cellulose and which was reflected in the nature of the resulting product. With increasing temperature there is an increase in the yields of the water-soluble derivatives and also a change in their relative abundance.

Solvolysis of 2-methyl[1-13C]-1-propyl tosylate was carried out in HOAc or CF3COOH without or with the presence of 2.0 equivalents of NaOAc or CF3COONa, respectively. Isobutyl, sec-butyl and tert-butyl products were obtained. With the use of 13C as label, isotopic scramblings were analyzed by 13C nmr, avoiding the necessity of chemical degradations associated with the use of 14C. There was no isotopic scrambling in the isobutyl product and scrambling of the 13C-label was observed only between C-2 and C-3 in the sec-butyl product, indicating 1,2-hydride shifts in the sec-butyl cation. In contrast to the involvement of equilibrating protonated methylcyclopropane intermediates observed in the trifluoroacetolysis of [1-14C]-1-butyl tosylate, the present results indicated that protonated methylcyclopropane intermediates did not play a significant role in the acetolysis or trifluoroacetolysis of isobutyl tosylate.