Showing papers on "Pyrazole published in 1972"

Synthesis and characterisation of rhodium(III) complexes containing nitrogen heterocyclic ligands

Abstract: The synthesis and characterisation of complexes of the type trans-[RhL4X2]Y (L = 3 or 4-substituted pyridine, 3,5-disubstituted pyridine, isoquinoline, pyrimidine, pyrazole, thiazole, X = Cl, Br and for L = py I; Y = univalent anion) are described. Using the same catalytic method, N-methylimidazole and ammonia give complexes of the type [RhL5X]2+(X = Cl or Br), whereas 5-chloro- and 5-nitro-N-methylimidazole give complexes of the type trans-[RhL5X2]2+. All the complexes of the type trans-[RhL4X2]+ and also [RhL5Cl]2+(L =N-methylimidazole) undergo catalytic substitutions, and the nature of the products is discussed.

Acylation of pyrazole containing polymers

Abstract: POLYMER COMPOSITIONS HAVING A MOLECULAR WEIGHT ABOVE 1000 AND CONTAINING THE REPEATING UNITS, DISTRIBUTED AT RANDOM: -AR-CH2-(1-X-PYRAZOL-5-3-YLENE)-, -AR-CH2-(2-X-PYRAZOL- 5,3-YLENE)-, -AR-(1-X-PYRAZOL-5,3-YLENE)-CH2-, AND -AR- (2-X-PYRAZOL-5-3-YLENE)-CH2- WHEREIN AR IS A DOVALENT RADICAL SELECTED FROM THE GROUP CONSISTING OF ALIPHATIC RADICALS, ALICYCLIC RADICALS, ALIPHATICALICYCLIC RADICALS, CARBOCYCLIC AND HETEROCYCLIC ARYL RADICALS AND X IS THE RADICAL OF AN ACID SELECTED FROM THE GROUP CONSISTING OF ORGANIC AND INORGANIC ACIDS AND SUBSTITUTED SUCH AACIDS.

Dérivés C‐glycosyliques VIII. Synthèse de C‐glycosyl‐3‐pyrazoles à partir d'une nitrilimine dérivée de l'anhydro‐2,5‐D‐ribose. Compétition entre cyclo‐additions dipolaires‐1,3 et cyclisations non concertés

Abstract: Several 3-(2,5-anhydro-ribosyl)-pyrazoles of potential medicinal interest have been synthesized by reacting alkynes or alkynylmagnesium bromides with the p-nitrophenylhydrazone of 2,5-anhydro-ribonyl bromide. From a mechanistic standpoint, it has been shown that the sugar-nitrilimine used in these studies reacts more readily as an electrophile than as a dipole. Thus, the hydrazonyl bromide gave exclusively the corresponding phenylethynylhydrazone when treated with phenylethynylmagnesium bromide and led to a 1:1 mixture of phenylethynylhydrazone and pyrazole when reacted with phenylacetylene. This proves that nucleophilic additions onto nitrilimines are much faster than Huisgen's 1,3-dipolar cycloadditions.

Pyrazolo (1,5a) 1,3,5-triazines

Abstract: WHEREIN R1, R2 and R3 are as defined hereinafter, or heterocyclic derivatives thereof. Also disclosed are substituted pyrazole derivatives which are used to prepare the pyrazolo(1,5a)1,3,5-triazines of this invention. D R A W I N G Pyrazolo(1,5a)1,3,5-triazines are disclosed which are useful as inhibitors of phosphodiesterase enzymes or intermediate in the production process. Such triazines are of the following general structure:

Pyrazolopyrimidine nucleosides. Part III. Synthesis of 1- and 2-(β-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidines from pyrazole nucleo-side derivatives

Abstract: The trimethylsilyl derivative (6) of 3-(3,3-dimethyl-1-triazeno)pyrazole-4-carboxamide (4) was condensed with 2,3,5-tri-O-acetyl-D-ribofuranosyl bromide (7) to give a mixture of nucleosides that were subsequently established as isomers rather than anomers. Removal of the blocking groups from one of the isomers furnished 5-(3,3-di-methyl-1-triazeno)-1-(β-D-ribofuranosyl)pyrazole-4-carboxamide (12) which was catalytically hydrogenated to afford the pyrazole analogue, 5-amino-1-(β-D-ribofuranosyl)pyrazole-4-carboxamide (13), of AICA riboside. Ring closure of (13) with formic acid-acetic anhydride followed by treatment with base furnished a mixture of nucleosides which were separated and characterized as 1-(β-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidin-4-one (16; allopurinol riboside) and 6-methyl-1-(β-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidin-4-one (17). The other isomer (8) furnished 3-(3,3-dimethyl-1-triazeno)-1-(β-D-ribofuranosyl)pyrazole-4-carboxamide (11) which was converted by a similar series of reactions into 2-(β-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidin-4-one (15).

Degenerate group movements. Degenerate acyl migrations in pyrazole chemistry

Abstract: Variable-temperature n.m.r. studies show the existence of degenerate NN-acyl migration in 1-anilinocarbonyl-3,5-dimethylpyrazole (Ia).

CIS-2-ACETYL-1-METHYL-1,2,3,3a,4,9b-HEXAHYDRO [1]BENZOPYRANO [4,3-C]PYRAZOLE

Abstract: The invention concerns a process for the production of an anellated or bridged N'-monosubstituted N-acyl pyrazolidine, characterized in that an olefinic aldehyde component comprising an olefinic aldehyde, or one of its reactive functional derivatives having its olefinic C/C double bond separated from the aldehyde by three to five atoms, of which one or two members may be contained in the same ring, and a hydrazine component comprising an N'-monosubstituted N-acl hydrazine, are reacted together with the removal of water. The invention furthermore extends to various compounds which may be produced by the process. The invention allows for production of a large class of novel pharmacologically active compounds.

Pyrazoles IX. Nitration of 1‐methyl‐4‐phenylpyrazole

Abstract: In contrast to nitration with nitric acid in sulfuric acid giving 4-(o,p-dinitrophenyl)-l-methylpyrazole 2, both the phenyl and the pyrazole ring are substituted on nitration with acetyl nitrate. With the latter method also a predominant ortho substitution in the phenyl ring is observed. It is concluded, that the pyrazole ring is quite susceptible to nitration at positions other than the, hitherto favoured, 4-position.

Potentially bifunctional reactants. Aromatic nucleophilic substitution by imidazole or pyrazole

Abstract: Quantitative N-2,4-dinitrophenylation of imidazole by 1-fluoro-(FDNB) or 1-chloro-2,4-dinitrobenzene (CDNB), or of pyrazole by FDNB occurs in benzene The kinetics of the reaction of FDNB with imidazole are third-order overall (second-order with respect to imidazole) at low imidazole concentration, while levelling off of the rate occurs at higher imidazole concentration Kinetics for the other reactions fit an equation containing terms both first- and second-order in the nucleophile These results are interpreted in terms of an addition–elimination mechanism, with decomposition of the intermediate into products being fast for CDNB and slow (involving bifunctional reactivity for pyrazole and monofunctional reactivity for imidazole) for FDNB

Reduction of some esters of pyrazole-3,4-dicarboxylic acid

Abstract: 3,4-Bishydroxymethylpyrazole was prepared by reduction of diethyl pyrazole-3,4-dicarboxylate and of SS-diethyl pyrazole-3,4-dicarbothioate. A reduction of dimethyl pyrazole-3,4-dicarboxylate to methyl 4-formylpyrazole-3-carboxylate is also described.

Cyclization of 2-(3-aryl-5-pyrazolyl)benzoic acids,esters and amides to 2-arylpyrazolo(5,1-a)isoindol-8-ones

Abstract: 1. THE PROCESS OF CONTACTING A COMPOUND OF THE FORMULA 3-(B-CO-(Y1,(X)N-1,2-PHENYLENE)-),4-R,5-R1-PYRAZOLE WITH A CONDENSING AGENT CONSISTING OF A LOWER ALKANOIC ANHYDRIDE IN THE PRESENCE OF A TERTIARY AMINE SELECTED FROM THE GROUP CONSISTING OF PYRIDINE, TRIMETHYLAMINE, TRIETHYLAMINE, 1,4-DIAZABICYCLO (2.2.2.) OCTANE, QUINUCLIDINE, QUINOLINE, THE 2-, 3- AND 4-PICOLINES, THE 2,3,4-, 2,3,52,3,5- AND 2,4,6-COLLIDINES, THE 2,3-, 2,4-, 2,5-, 2,6-, 3,4AND 3,5-LUTIDINES, 1,4 - DIMETHYLPIPERAZINE, 4 - DIMETHYLAMINOPYRIDINE AND N,N-DIMETHYLANILINE, AT A TEMPERATURE RANGE OF 20-100*C. FROM 15 MINUTES UP TO 8 HOURS AND RECOVERING A PRODUCT OF THE FORMULA 2-R1,3-R,8-(O=),Y1,(X1)N-PYRAZOLO(5,1-A)ISOINDOLINE WHEREIN X1 IS H, C1, BR OR F; Y1 IS H, ALKYL OF 1 TO 4 CABON ATOMS, ALKOXY OF 1 TO 4 CARBON ATOMS, OR CF3; N IS A WHOLE NUMBER 1, 2, OR 3; R IS H, ALKYL OF 1 TO 4 CARBON ATOMS, OR TOGETHER WITH X IS -CH2-, -CH2CH2-, OR CH=CH- CONNECTING THE 4-POSITION OF THE PYRAZOLE RING TO THE 2-POSITION OF THE R1 SUBSTITUENT; R1 IS TERT-ALKYL OF 4 THROUGH 12 CARBON ATOMS, NAPHTHYL, PHENANTHRYL, X,Y,Z-PHENYL-, FUR-2-YL-, THIOPHEN-2-YL-, OR PYRIDINYL- IN WHICH X IS H, HALOGEN, ALKYL OF 1 TO 4 CARBON ATOMS, ALKOXY OF 1 TO 4 CARBON ATOMS, ALKYLTHIO OF 1 TO 4 CARBON ATOMS NO2, CH3SO2, CF3, CN, OR CARBOALKOXY OF 1 TO 4 CARBON ATOMS, Y IS H, HALOGEN, ALKOXY OF 1 TO 4 CARBON ATOMS OR ALKYL OF 1 TO 4 CARBON ATOMS; Z IS H, HALOGEN, ALKOXY OF 1 TO 4 CARBON ATOMS, OR ALKYL OF 1 TO 4 CARBON ATOMS; B IS OM OR NR2R3, IN WHICH M IS H, BENZYL, OR ALKYL OF 1-6 CARBON ATOMS, OPTIONALLY SUBSTITUTED WITH HYDROXY OR HALOGEN; AND R2 AND R3 ARE EACH HYDROGEN OR ALKYL OF 1 TO 6 CARBON ATOMS.

Multi-step process for preparing 1-(substituted-hydrocarbyl)-3,4,5-tribromopyrazoles

Abstract: This chemical process invention provides 3,4,5-tribromopyrazole by direct tribromination of pyrazole in an aqueous reaction medium with alkali metal hydroxide. It further provides N-alkylation in the same aqueous alkaline medium to obtain 1-(substituted-hydrocarbyl)-3,4,5-tribromopyrazoles useful as herbicides.

Acetylene derivatives of heterocycles

Abstract: 4-Ethynyl-1,3,5-trimethylpyrazole and 3,5-diethynyl-1-methylpyrazole have been synthesized by the reaction of the corresponding methyl N-methyl-pyrazolyl ketones with PCl5 followed by dehydrochlorination. 4-Butadiynyl-1,3,5-trimethylpyrazole has been obtained similarly from 4-acetoacetyl-1,3,5-trimethylpyrazole. The N-substituted pyrazolylacetylenes have been subjected to the Chodkiewicz-Cadiot reaction and to dehydrocondensation. The IR spectra of the acetylene derivatives of pyrazole synthesized are discussed.

The influence of pyrazole on ethanol-induced changes in carbohydrate metabolism of the liver.

Abstract: The effect of pretreatment with 340 μg/g pyrazole i.p., an inhibitor of alcohol dehydrogenase, on the changes in the carbohydrate metabolism of the liver, as produced by 4 mg/g ethanol i.v., was investigated in mice. Pyrazole completely prevented the ethanol-induced rise of the glycerol-1-phosphate content and of the glycerol-1-phosphate/dihydroxyacetone phosphate and lactate/pyruvate ratios and diminished the decrease of the hepatic pyruvate and lactate contents. This suggests, that these changes are mediated by shifts in the hepatic NADH/NAD ratio occurring during alcohol oxidation. The glycogen depleting effect of ethanol was not abolished by pyrazole showing that this effect is brought about—at least in part—by ethanol itself.

Heterocyclic analogs of xanthones

Abstract: Thiochromono[3,2-d]pyrazoles are formed by the action of potassium hydrosulfide on 5-chloro-4-(o-chlorobenzoyl)pyrazoles. The action of Grignard reagents on them gave 4-dimethylaminopropylidenethiochromonopyrazoles, which are structural analogs of known medicinal substances.

Hydroformylation process and catalyst

Abstract: 1281389 Oxo process and catalyst BP CHEMICALS Ltd 11 Nov 1970 [2 Dec 1969] 58775/69 Headings C2B and C2C Aldehydes are prepared by the hydroformylation of olefines in the presence of novel complexes of Group VIII metals other than Fe, Ni, Pd or Pt which contain a bidentate anionic ligand co-ordinating through 2 nitrogen atoms. Specified catalysts comprise the reaction products of rhodium dicarbonyl chloride dimer with di-imino alkane such as 2,4-di-o-tolyl-iminopentane giving a product of the type (2 - o - tolylimino - 4 - o - tolylaminopent - 2- en-ato dicarbonyl rhodium or with (1-pyrazolyl) borates giving complexes of type where M is the Group VIII metal. The pyrazole ring may be substituted. The catalyst may also contain at least one neutral complexing ligand containing an atom of a Group Vb or VIb element having a single pair of electrons available for donation. Examples prepare normal and branched aldehydes from propene and hexene-1.