Synthesis and reactions of 4-isopropylidene-1-aryl-3-methyl-2-pyrazolin-5-ones

The reactions of 4-isopropylidene-1-aryl-3-methyl-2-pyrazolin-5-ones 4a-d were investigated under a variety of conditions. In the presence of thiols or piperidine, 4a-d failed to yield conjugate addition products, presumably due to the steric bulk provided by the two methyl substituents of the isopropylidene side chain. Reaction of 4a-d with hydrazine derivatives gave the 1-aryl-3-methyl-2-pyrazolin-5-ones 3a-d and isopropyl-hydrazones. Treatment of 4a with potassium cyanide yielded a stable conjugate addition product which exists as a mixture of tautomers in different solvents. Also, oxidation of 4a with hydrogen peroxide gave a spiroepoxide 22 , while m-chloroperbenzoic acid oxidation afforded both the spiroepoxide 22 , and a small quantity of a hydroxyspiroepoxide 23.     

A new synthesis of 3-amino-1-aryl-2-pyrazolin-5-ones

Reaction of ethyl 3-nitropropionate with aryldiazonium chlorides in basic medium yields ethyl 3-nitro-3-(arylhydrazono)propionates. These α-nitrohydrazones are converted by catalytic hydrogenation to 3-amino-1-aryl-2-pyrazolin-5-ones, probably via cyclization of intermediate amidrazones produced in situ. This appears to be the first route to the title compounds that does not use a substituted phenyl hydrazine intermediate and offers advantages in the preparation of pyrazolinones bearing electron-rich aryl rings.     

The mass spectra of some 4-arylhydrazono-3-methyl-2-pyrazolin-5-ones

The mass spectra of the title compounds, having various substituents on the aryl group are presented and discussed. High resolution mass measurements and metastable ions allow the fragmentation to be rationalized. The system is typified by the occurrence of intense molecular ions and of ions due to consecutive decomposition of the nitrogen-containing part of the molecule. Ions attributable to substituted, aniline-like fragments, and their decomposition products, are also abundant and may be used to identify the aryl group present.     

Extraction of scandium ions by 1-alkyl-3-methyl-2-pyrazolin-5-ones from perchlorate solutions

The extraction of perchloric acid and the two-phase partition of 1-alkyl-3-methyl-2-pyrazolin-5-ones (AMPs) in the system water-chloroform-perchloric acid are studied. These reagents can extract scandium cations from weak acid solutions in the presence of perchlorate ions. 1-Alkyl-3-methyl-2-pyrazolin-5-ones separate aqueous perchloric acid solutions into a pair of liquid phases. Scandium ions concentrate in the lower phase, which has a small volume.     

Spirobutyrolactone derived from 1-phenyl-3-methyl-2-pyrazolin-5-one

X-ray diffraction and NMR spectral examination have shown that 1-phenyl-3-methyl-2-pyrazolin-5-one reacts with methyl acrylate in methanol to give spiro[(1-phenyl-3-methyl-2-pyrazolin-5-one)-4,5-butyrolactone]. The conformation has been shown to be the same in the crystal and in solution, the pyrazoline ring has been found to be nonplanar, the reasons for the acoplanarity established, stabilizing and destabilizing interactions studied, and the orientation of the phenyl substituent relative to the pyrazolin-5-one ring determined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 909–913, July, 1988.     

Structure and Extractive Ability of 1-Alkyl- and 3-Methyl-1-phenyl-2-pyrazolin-5-ones

Extractive ability of 1-substituted 3-methylpyrazol-5-ones (LH) is studied. From acidic chloride complexes, ionic thallium(III) associates (LH₂)[TlCl₄] are extracted; from trichloroacetate, coordination scandium complexes Sc(LH)₄(CCl₃COO)₃; and from ammine, copper(II) complexes CuL₂. The extractive ability decreases in the order R = C₇H₁₅ > C₆H₁₃ > C₅H₁₁ > C₆H₅ > C₄H₉.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 2, 2005, pp. 326–330.Original Russian Text Copyright © 2005 by Lesnov, Sazonova, Pavlov.     

Photochemical benzyl migration in 3-pyrazolin-5-ones

The 3-pyrazolin-5-ones ($\text{1}$) undergo light induced rearrangement by N-O and N-G benzyl migrations. A free radical mechanism is proposed.     

A convenient synthesis of 1-aryl-3-methyl-1,2,4-triazolin-5-ones from the reaction between acetone arylhydrazones and acetyl isocyanate

The reaction of acetone arylhydrazones with acetyl isocyanate gave the corresponding 4-acetyl-1-aryl-3,3-dimethyl-1,2,4-triazolidin-5-ones which eliminated acetone upon acidic hydrolysis to give 1-aryl-3-methyl-1,2,-4-triazolin-5-ones. The above transformation can be achieved in one pot by a simple solvent swap.     

The reaction rate of edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one (MCI-186)) with hydroxyl radical

The pyrazoline derivative edaravone is a potent hydroxyl radical scavenger that has been approved for attenuation of brain damage caused by ischemia-reperfusion. In the present work, we first determined the rate constant, k(r), at which edaravone scavenges radicals generated by a Fenton reaction in aqueous solution in the presence of the spin trap agent, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), which competed with edaravone. We detected the edaravone radicals in the process of hydroxyl radical scavenging and found that edaravone reacts with hydroxyl radical around the diffusion limit (k(r)=3.0 x 10(10) M(-1) s(-1)). The EPR (electron paramagnetic resonance) spectrum of the edaravone radical was observed by oxidation with a horseradish peroxidase-hydrogen peroxide system using the fast-flow method. This radical species is unstable and changed to another radical species with time. In addition, it was found that edaravone consumed molecular oxygen when it was oxidized by horseradish peroxidase (HRP)-H(2)O(2) system, and that edaravone was capable of providing two electrons to the electrophiles. The possible mechanisms for oxidation of edaravone were investigated from these findings.     

Synthesis of 1-Aminocarbonylmethyl-5-aryl-4-aroyl-3-hydroxy-3-pyrroline-2-ones

Russian Journal of General Chemistry - A series of new 1-aminocarbonylmethyl-5-aryl-4-aroyl-3-hydroxy-3-pyrrolin-2-ones has been synthesized through a three-component reaction of aroylpyruvic acid...     

Synthesis and structure of fluorine-containing 3-pyrazolin-5-ones

Noncatalyzed reaction of α-acetyl-γ-butyrolactones containing a polyfluoroalkyl substituent in the γ-position with hydrazine hydrate and thiosemicarbazide in methanol leads to the formation of substituted 3-pyrazolin-5-ones that in (CD₃)₂SO solution and in the solid state exist in the NH-tautomeric form.     

Effective synthesis of 5-aryl-3-ethylidene-3H-pyrrol-2-ones

Substituted 5-aryl-3-ethylidene-3H-pyrrol-2-ones were synthesized by the reaction of the corresponding 4-aryl-4-oxobutanoic acids with ketones in the presence of aminating agents. The conditions of this reaction were developed with the use of both the conventional condensation technique and microwave activation. The structures of the reaction products were con-firmed by elemental analysis, IR spectroscopy, and ¹H NMR spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 693–696, April, 2006.     

Synthesis of 3-aryl-5-dichloromethyl-1H-pyrazole-1-carboxamides from 1-aryl-3,4,4-trichlorobut-3-en-1-ones

The reaction of 1-aryl-3,4,4-trichlorobut-3-en-1-ones with semicarbazide hydrochloride in the presence of sodium acetate is accompanied by prototropic allylic rearrangement, leading to the formation of two isomeric products, semicarbazones of the initial ketones and 1-aryl-3,4,4-trichlorobut-2-en-1-one semicarbazones. The latter undergo heterocyclization in the presence of triethylamine to give the corresponding 3-aryl-5-dichloromethyl-1H-pyrazole-1-carboxamides.     

Reactions with 1(2H)-phthalazinones, 4,5-dihydro-3(2H)-pyridazinones and 3-pyrazolin-5-ones

The condensation of 1(2H)-phthalazinones (Ia-c), 4,5-dihydro-6-phenyl-3(2H)-pyridazinone (IIIa), and 4-arylidene-4,5-dihydro-6-phenylpyridazinones (IVa-b) with secondary amines and formaldehyde yields the corresponding N-Mannich-bases (Id, IIIc-d, and IVi-j, respectively). Similarly, reaction with acrylonitrile, affords the cyanoethylated products (Ig, IIIf, and IVk-1, respectively). The Mannich-bases (Id) are also obtained by reaction of the appropriate amines with the corresponding chloromethyl- (If), or hydroxymethylphthalazinone derivatives (Ie); and by treatment of the hydroxymethyl derivative of IIIa with the same reagents. In the presence of ethyl-amine, the condensation of la-c with formaldehyde yields the corresponding bis-derivatives (II).The reaction of 3-methyl-2-phenyl-3-pyrazolin-5-one (Va) with formaldehyde and piperidine or morpholine involves the hydrogen atom on C₄ with formation of the Mannich-bases (Vd-e). In addition, the synthesis of some of the corresponding bis-derivati es (VI) are reported. The IR spectra of the reaction products are discussed. Interaction of Vd with aromatic thiols leads to the formation of 4-arylthiomethyl-3-methyl-2-phenyl-3-pyrozolin-5-ones (IVf-i). The latter compounds react with ethereal diazomethane yielding products believed to have structures similar to VII.Treatment of 2-N-piperidinomethyl-4-phenyl-1(2H)-phthalazinone (cf. Id), and 2-N-piperidino-methyl-6-phenyl-4,5-dihydro-3(2H)-pyridazinone (IIIe) with phenylmagnesium bromide, followed by hydrolysis, gives 1,4-diphenylphthalazine and 3,6-diphenylpyridazine (VIII), respectively. The latter has also been obtained by the action of the same reagent on IIIa and/or 6-phenyl-3(2H)-pyridazinone.     

Synthesis of cis-1-methyl-2-aryl-3-aroylaziridines

trans-1-Methyl-2-aryl-3-aroylaziridines readily undergo epimerization to give the corresponding cis isomers in high yields in the presence of catalytic amounts of quaternary ammonium bases (trimethylbenzylammonium or triethylmethylammonium hydroxide). The structures of the compounds obtained were established on the basis of the IR and PMR spectra and the results of elementary analysis.Translated from Khimiya Geterotsilicheskikh Soedinenii, No. 10, pp. 1353–1355, October, 1980.