Showing papers on "Pyrazole published in 1973"

Synthesen mit Nitrilen, XXXV. Reaktionen von Tetracyanäthylen mit Heterocyclen

Abstract: Bei der Umsetzung von Tetracyanathylen mit Barbitursauren werden in Abhangigkeit von der Reaktionstemperatur Tetrahydro-2H-pyrano[2.3-d]pyrimidine (2a, b) oder Dipyrimidinylmalodinitrile (3a, b) erhalten. 1,3-Disubstituierte 5-Pyrazolone reagieren in ahnlicher Weise. Aus 3-Aminopyrazolen und Tetracyanathylen entstehen unter Eliminierung von HCN (Tricyanvinyl)pyrazole (12a, b), welche zu Pyrazolo[3.4-b]pyridinen (13a–c) cyclisiert werden konnen. Syntheses with Nitriles, XXXV. Reactions of Tetracyanoethylene with Heterocyclic Compounds The reaction of tetracyanoethylene with barbituric acids yields tetrahydro-2H-pyrano[2.3-d]-pyrimidines (2a, b) or dipyrimidinylmalonodinitriles (3a, b) depending on the reaction temperature. 1,3-Disubstituted 5-pyrazolones react in a similar way. Reaction of 3-amino-pyrazoles with tetracyanoethylene results in elimination of HCN and formation of (tricyanovinyl)pyrazoles (12a, b), which cyclize to pyrazolo[3.4-b]pyridines (13a–c).

Pyrazoles and imidazoles as ligands. Part xviii: Neutral and anionic pyrazole coordinated to Cu(I) and Ag(I)

Abstract: A few compounds having the general formula M(L)+2 X− are reported, in which M(I) = Cu or Ag, X− = BF−4, NO−3, Cl−, Br−, and L stands for pyrazole, 3(5)-methylpyrazole and 4-nitropyrazole. The compounds are formed by reaction of MX and L in acidic medium. Infrared spectra of the compounds are consistent with linear cations ML+2 and uncoordinated anions. Apart from the above compounds, a different class of compounds is formed in less protic media. These compounds are salt like and have the formula M+L−, with M+ = Cu+ and Ag+ and L = pyrazole, 4-iodopyrazole, 4-bromopyrazole, 4-ethylpyrazole, 4-nitropyrazole and 3(5)-methylpyrazole. Infrared spectra, mass spectra, X-ray powder diagrams and solubility studies indicate that these compounds are at least trimeric and possibly polymeric with bridging pyrazolate anions between the metal ions.

Esters of phosphorus oxy-acids as alkylating agents. Part II. N-Alkylation of imidazole and related heterocyclic compounds with trialkyl phosphates

Abstract: A new method for N-alkylation of imidazole, benzimidazole, pyrazole, 1,2,4-triazole, and benzotriazole using trimethyl, triethyl, and tri-n-butyl phosphates as alkylating agents is described. All these heterocycles are easily converted into the corresponding N-alkyl derivatives in 45–90% yields. Predominant alkylation at N-1 was observed in both triazoles.

Substituted indeno, naphtho and cyclohepta pyrazoles

Abstract: Substituted indeno [1,2-c] pyrazoles, naphtho [1,2-c] pyrazoles and benzo [6,7] cyclohepta [1,2-c] pyrazoles e.g., 3-(2,3-dimethoxyphenyl)-4H-indeno[1,2-c] pyrazole and 4,5-dihydro-3-(4-pyridyl)-2H-naphtho[1,2-c] pyrazole, are useful as non-estrogenic anti-fertility agents and antihypertensive agents.

Pyrazole plant growth regulants

Abstract: Substituted pyrazole compounds have been found to be effective plant growth regulants. Exemplary of the effective compounds are 3-(2-carboxyphenyl)-5-phenyl-pyrazole, its 2-ethanolamine salt, and 3-(2-carboxy-1-cyclohexen-1-yl)-5-phenylpyrazole.

Central nervous system interaction of pyrazole and ethanol in the rat.

Abstract: The degree of impairment of a motor performance test under the influence of alcohol (1.4–2.0 g/kg) was increased progressively by increasing doses of pyrazole (0–3.5 mmol/kg), which had no discerni...

Process for preparing substituted indeno,naphtho and cyclohepta pyrazoles

Abstract: Substituted indeno (1,2-c) pyrazoles, naphtho (1,2-c) pyrazoles and benzo (6,7) cyclohepta (1,2-c) pyrazoles e.g., 3-(2,3dimethoxyphenyl)-4H-indeno(1,2-c) pyrazole and 4,5-dihydro-3-(4pyridyl)-2H-naphtho(1,2-c) pyrazole, are useful as non-estrogenic and anti-fertility agents and antihypertensive gents and are prepared by treating substituted indanones, Alpha -tetralones and benzosuberones with alkylphenylsulfonyl hydrazine.

Photochemical generation of a vinylketen from 5-acetyl-3,3-dimethyl-3H-pyrazole and the identification of the end products as 7-acetyl-3,5,5,9,9-pentamethyl-1,6-diazabicyclo[4,3,0]nona-3,7-dien-2-one by X-ray crystallographic analysis

Abstract: The direct photolysis (λ > 290 nm) of 5-acetyl-3,3-dimethyl-3H-pyrazole (1) in ether gives 2-acetyl-1,1-dimethylcyclopropane (4; 5%) and 7-acetyl-3,5,5,9,9-pentamethyl-1,6-diazabicyclo[4,3,0]nona-3,7-dien-2-one (7; 46%), the structure of which has been determined by X-ray crystallography; the latter compound is formed via a vinylketen (6), which can be trapped with dimethylamine as the amide (5) and with azobenzene as the [2+2] adduct (8).

Condensed thiophen ring systems. Part XI. Synthesis of 2-aryl[1]-benzothieno[3,2-c]pyrazoles and 2-aryl[1]benzothieno[2,3-c]pyrazoles

Abstract: 2-Aryl[1]benzothieno[3,2-c]pyrazoles were prepared by reductive cyclisation of the corresponding N-(3-nitrobenzo[b]thiophen-2-ylidene)anilines with triethyl phosphite (20–30% yields) and by thermolysis in bis-(2-methoxyethyl) ether of the corresponding N-(3-azidobenzo[b]thiophen-2-ylidene)anilines (70–75% yields). Treatment of N-(2-nitrobenzo[b]thiophen-3-ylidene)anilines with triethyl phosphite gave mixtures of the corresponding 2-aryl[1]benzothieno[2,3-c]pyrazoles and benzo[b]thiophen-3-carbonitrile, whilst pyrolysis of N-(2-azidobenzo[b]thiophen-3-ylidene)aniline in bis-(2-methoxyethyl) ether gave a mixture of 2-phenyl[1]benzothieno[2,3-c]pyrazole and the anil of 2,3-dihydro-2-oxobenzo[b]thiophen-3-carbonitrile. Mechanistic aspects are discussed.

The synthesis of 2-Alkyl- and 2-Acyl-imidazoles by substitution methods

Abstract: Imidazole and some 1-alkylimidazoles are methylated at C2 under homolytic methylation conditions. Pyrazole forms 3-methylpyrazole, while 2-substituted imidazoles are unaffected. Some 2-acylimidazoles are prepared and described.

Water-soluble disazo compounds containing a pyrazole component

Abstract: Water-soluble disazo dyes of the pyrazole series of the formula A and B each being hydrogen, methyl or phenyl; X being a phenyl or naphthyl radical; Y being a divalent phenylene or naphthylene radical; R being hydrogen or an organic radical; and n being 1 or 2. The dyes are especially suitable for dyeing and printing natural and synthetic polyamides and basified textile material and also for dyeing cellulose fibers, particularly when they contain reactive radicals.

Radiation Chemistry of Nitrogen and Sulfur Heterocyclics

Abstract: The gamma radiolysis of nitrogen and sulfur heterocyclics having one or more nitrogen or sulfur atoms in five- and six-membered rings was studied. G values are given for the major gaseous products identified by gas chromatography for the radiolyses of pyrrole, pyrazole, imidazole, 1,2,4-triazole, tetrazole, pyrazine, pyrimidine, 1,3,5-triazine, benzotriazole, thiazole, isothiazole, and thiophene. The principal gaseous product formed during the γ-radiation of five- and six-membered nitrogen heterocyclics was hydrogen except that compounds having two adjacent nitrogen atoms in the ring produced large amounts of nitrogen and other gaseous products. When the N atoms are separated by carbon atoms, no nitrogen gas is produced and the G values for gas production are very low. Thiophene has greater stability to radiation than pyrrole as far as gas production is concerned. However, the introduction of a second heteroatom (nitrogen in the case of thiazole and isothiazole) in the five-membered ring containing sulfur...

Aromatic heteroanionic species. Part I. Proton nuclear magnetic resonance spectra of the anions of five-membered aza-heterocycles

Abstract: Anions derived from five-membered aza-heterocycles and their benzo-condensed derivatives have been investigated by 1H n.m.r. spectroscopy. A consistent high-field shift is found for the anionic species relative to the corresponding neutral precursors. No appreciable variation occurs in ring-current effects upon metallation of polymethylene-bridged derivatives of pyrrole and pyrazole. Indolylsodium is shown to be a solvent-separated species when in dimethyl sulphoxide or in tetrahydrofuran in the presence of 1,2:10,11-bistetramethylene[18]crown-6 ether: evidence is presented for mixtures of intimate and solvent-separated ion-pairs in tetrahydrofuran and dimethoxyethane solutions. The nature of indolyl Grignard salts is discussed in the light of the foregoing results.

The kinetics and mechanism of the electrophilic substitution of heteroaromatic compounds. Part XXXIV. The hydrogen-exchange rates of methylpyrazoles

Abstract: Acid-catalysed hydrogen-exchange rates are recorded for 1-methylpyrazole and for its 3-, 4-, and 5-mono- and 3,4-, 3,5-, and 4,5-dimethyl derivatives, together with those for the corresponding 2-methylpyrazolium cations. The rates have been extrapolated to give rate constants at 100° and pH 0: these are discussed with reference to the effect of the methyl groups and of the two cyclic pyrazole nitrogen atoms on electrophilic substitution rates.

Synthesis of Pyrazole Derivatives Using 1-Benzoyl-1-phenylhydrazine

Abstract: Condensation of 1-benzoyl-1-phenylhydrazine (I) with β-ketoesters and β-diketones was investigated. Reaction of I with ethyl acetoacetate, ethyl benzoylacetate and diethyl acetonedicarboxylate in the presence of phosphorus pentoxide afforded the corresponding hydrazones which were easily cyclized by sodium hydroxide to give pyrazole derivatives. Reaction of I with acetylacetone proceeded to give hydrazone without condensing agent. 4-Carboxy-1,5-diphenylpyrazol-3-ylacetic acid and its mono- and diester were also prepared.

Pyrazole-5-carboxamides

Abstract: 3-Methyl-N-(1-pyrrolin-2-yl)-pyrazole-5-carboxamides and processes for making same. Such compounds lower blood sugar and, hence, are useful as antidiabetic agents.