Deprotonation of pyrazole and its analogs by aqueous copper acetate in the presence of triethylamine

Deprotonation reactions of pyrazole and its analogs by aqueous copper acetate in benzene at room temperature in the presence of triethylamine were studied. Unlike 3,5-dimethylpyrazole, more acidic pyrazole, 5-methyl-3-trifluoromethylpyrazole, and 3,5-bis(trifluoromethyl)pyrazoles are deprotonated to give pyrazolate bridges. The structural features of the obtained compounds are discussed based on X-ray diffraction data.     

Unusual behavior of 3,5-dimethylpyrazole in the aza-Michael reaction with crotonaldehyde in aqueous medium

Russian Journal of Organic Chemistry - The aza-Michael reaction of 3,5-dimethylpyrazole with crotonaldehyde in water involved addition of two aldehyde molecules with formation of...     

Synthesis and structure of palladium triflates with coordinated 3,5-dimethylpyrazole

We discovered that reacting Pd₃(??-OOCMe)₃ with two moles of trifluoromethanesulfonic acid (Hotf) and then with four moles of 3,5-dimethylpyrazole (Hdmpz) in acetonitrile and benzene produces, in high yields, [Pd(Hdmpz)₄](otf)₂ and Pd(Hdmpz)₄(HOOCMe)₂(otf)₂, respectively. Reacting PhenPd(OOCMe)₂ with Hotf in MeCN yields PhenPd(NCMe)₂(otf)₂, where labile acetonitrile molecules are substituted by Hdmpz under mild conditions to form PhenPd(Hdmpz)₂(otf)₂. The structures of complexes have been solved on the basis of X-ray crystallography data.     

Reactions of 4-acylresorcinol derivatives with 3,5-di-tert-butyl-4-hydroxybenzyl acetate

Reactions of hydroxyphenylcarbonyl derivatives with 3,5-di-tert-butyl-4-hydroxybenzyl acetate under mild conditions gave novel functionalized diarylmethanes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1128–1133, July, 2006.     

Reactions of 2,3-epoxypolyfluoroalkanes with triethylamine

The reactions of 2,3-epoxyperfluoro- and 2,3-epoxy--hydropolyfluoroalkanes with excess triethylamine at elevated temperatures yield secondary alcohols, which are the reduction products of intermediate isomeric ketones. Ring-opening occurs preferentially from the side of the less bulky trifluoromethyl group in all compounds except 2,3-epoxy-6-hydroundecafluorohexane.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2177–2181, December, 1994.     

Vibrational spectra of 3,5-dimethylpyrazole and deuterated derivatives

The infrared (IR) and Raman spectra of 3,5-dimethylpyrazole have been recorded in the vapor, liquid (melt and solution) and solid states. Two deuterated derivatives, C5H7N-ND and C5D7N-NH, were also studied in solid state and in solutions. Instrumental resolution was relatively low, 2.0 cm(-1) in the IR and approximately 2.7 cm(-1) in the Raman spectra. The solids are made of cyclic hydrogen-bonded trimers. These trimers, present also in chloroform and acetone solutions, give rise to characteristic high absorption IR spectra in the 3200-2500 cm(-1) region, related to Fermi resonance involving nu(NH) vibrations. Bands from trimers are not present in water solutions but these solutions show spectral features similar in several ways to those of the trimer, attributable to solvent-bonded complexes. Evidence of H-bonding interactions with the other solvents is also visible in the high-frequency region. The two very intense bands in the Raman spectra of the solids appearing at 115 and 82 cm(-1) in the parent compound are also connected with a trimer formation. To interpret the experimental data, ab initio computations of the harmonic vibrational frequencies and IR and Raman intensities were carried out using the Gaussian 94 program package after full optimization at the RHF/6-31G* level for the three monomeric compounds as well as for three models of the trimer, with C3h, C3 and C1 symmetry. The combined use of experiments and computations allow a firm assignment of most of the observed bands for all the systems. In general, the agreement between theory and experiment is very good, with the exception of the IR and Raman intensities of some transitions. Particularly noticeable is the failure of the theoretical calculation in accounting for the high intensity of the Raman bands of the solid about 115 and 82 cm(-1).     

Copper(II) trimethylacetate complexes with 3,5-dimethylpyrazole

Specific features of the chemical behavior and structure of copper(II) trimethylacetate complexes with 3,5-dimethylpyrazole have been considered based on X-ray crystallographic data.     

Reactions of derivatives of phosphorylacetic acid hydrazides with 3,5-di-tert-butyl-4-hydroxybenzyl acetate

Abstract

To obtain new polyfunctional inhibitors of radical-chain oxidative processes, C- and N-benzylation of a number of phosphorylacetic acid hydrazide derivatives is realized in their reactions with 3,5-di-tert-butyl-4-hydroxybenzyl acetate. N-benzylation of mixtures of Z and E isomers of hydrazones of phosphorylacetic acid derivatives proceeds stereoselectively with the formation of only E_C=N isomers.     

Reactions of triacetylmethane with monosubstituted hydrazines and amidine analogues. Syntheses of 4-acetyl-3,5-dimethylpyrazole amidinohydrazone and 1,3,5-triazine derivatives

Triacetylmethane ( 1 ) reacts with amidinohydrazines in acidic medium to afford 4-acetyl-3,5-dimethylpyrazole amidinohydrazone derivatives 2,4 . However, a similar reaction of 1 with thiosemicarbazide or semicarbazide led mainly to 3,5-dimethylpyrazole ( 6 ). The great propensity of 1 to hydrolysis accounts for this last transformation, as well as for the fact that with guanidine it led to 2-amino-4,6-dimethylpyrimidine ( 10 ) and with S-methylisothiourea it provided the unexpected 2-amino-4-methyl-6-methylthio-1,3,5-triazine ( 11 ).     

Rhenium(IV) and rhenium(V) complexes with 3,5-dimethylpyrazole

Mono-and dinuclear Re^IV and Re^V complexes with 3,5-dimethylpyrazole (Me₂pzH) were synthesized. The cis-[Re₂O₃Cl₄(3,5-Me₂pzH)₄] complex (cis-1) was prepared by the reaction of NH₄ReO₄ with K[HB(Me₂pz)₃] in concentrated HCl or by refluxing of [ReCl₃(MeCN)(PPh₃)₂] with Me₂pzH in air. The bromide complex trans-[Re₂O₃Br₄(3,5-Me₂pzH)₄] (trans-2) was synthesized by passing dry HBr through a solution of [Re₂O₃Br₂(μ-3,5-Me₂pz)₂(3,5-Me₂pzH)₂] (4) in chloroform. The pyrazolate-bridged complex [Re₂O₃Cl₂(μ-3,5-Me₂pz)₂(3,5-Me₂pzH)₂] (3) was prepared from (Et₄N)₂[ReOCl₅] or Cs₂[ReOCl₅] and Me₂pzH. The corresponding bromide and iodide complexes [Re₂O₃X₂(3,5-Me₂pz)₂(3,5-Me₂pzH)₂] · C₆H₆ (X = Br (4) or I (5)) were synthesized by the reactions of (NH₄)₂[ReBr₆] or K₂[ReI₆], respectively, with Me₂pzH. The [ReO(OMe)(3,5-Me₂pzH)₄]Br₂ · · 3,5-Me₂pzH · 4H₂O complex (6) was obtained as a by-product in the synthesis of complex 4. The reaction of [ReNCl₂(PPh₃)₂] with Me₂pzH was accompanied by hydrolytic denitration giving rise to the mixed-ligand complex [Re₂O₃Cl₂(μ-3,5-Me₂pz)₂(3,5-Me₂pzH)(PPh₃)] (7). The reaction of (NH₄)₂[ReBr₆] with a Me₂pzH melt gave the trans-[ReBr₄(3,5-Me₂pzH)₂] · · Me₂CO complex (8). The structures of complexes 2 and 4–8 were established by X-ray diffraction. All compounds were characterized by elemental analysis, electronic absorption spectroscopy, ¹H NMR and IR spectroscopy, mass spectrometry, and cyclic voltammetry. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 52–59, January, 2006.     

Alkylating nucleosides. 3. The reaction of 3,5-dimethylpyrazole nucleosides with N-bromosuccinimide

Bromination of 3,5-dimethylpyrazole nucleosides with N-bromosuccinimide gave the corresponding 4-bromo-3,5-dimethylpyrazole, 3-methyl-5-(bromomethyl)pyrazole and 4-bromo-3-methyl-5-(bromomethyl)pyrazole nucleosides. Structural assignments were made on basis of analytical and ¹ H nmr spectral data. All of the bromomethylpyrazole nucleosides described showed cytostatic activity against HeLa cell sultures.     

Copper(I) complex with BINAP and 3,5-dimethylpyrazole: synthesis and photoluminescent properties

1. Download : Download high-res image (55KB)
2. Download : Download full-size image

     

Cycloaddition Reactions of 3,5-DI-t-Butyl-o-Benzoquinone and Masked 3,5-DI-t-Butyl-o-Benzoquinones with Substituted Acetylenes)

Cycloadditions of 3,5-di-t-butyl-o-benzoquinone with diphenylacetylene, dimethyl acetylenedicarboxylaet, 3-hexyne, phenylacetylene, methyl propiolate, 1-octyne and 3-hydroxy-3-methyl-1-butyne were studied. The reactions occur periselectively across the diene moiety of 3,5-di-t-butyl-o-benzoquinone to give bicyclo[2.2.2]octa-5,7-diene-2,3-diones. In the cases of monosubstituted acetylenes, the reactions take place regioselectively. The selectivities are explained in terms of electronic and steric effects. The cycloadditions of two masked 3,5-di-t-butyl-o-benzoquinones 7 and 8 with monosubstituted acetylenes, phenylacetylene, methyl propiolate, 1-octyne and 3-hydroxy-3-methyl-1-butyne were also examined. Compound 7 reacts with high regioselectivity to give only bicyclo[2.2.2]octa-5,7-diene-2,3-diones 10 upon subsequent hydrolysis; the high regioselectivity was explained as the result of coherent electronic and steric effects. Compound 8 reacts with monosubstituted acetylenes to give either 9 or 10 or both upon subsequent hydrolysis, depending on the nature of the substituents on acetylene. This results from the opposite influences of electronic and steric effects.     

Reactions of oxalyl chloride with 1,2-cycloalkanediols in the presence of triethylamine

The relationship between the product patterns and the configurations of 1,2-cycloheptane- and 1,2-cyclooctanediols 9 in the cyclocondensations with oxalyl chloride in the presence of triethylamine at 0 degrees C has been shown analogous to that obtained for 1,2-disubstituted acyclic ethylene glycols 1: cis-1,2-cyclooctanediol (9f) produced the cyclic oxalate 14f as the major product, while trans-1,2-cycloheptanediol (9e) and trans-1,2-cyclooctanediol (9g) formed the cyclic carbonates 12e, g as the major products. On the other hand, the cyclic oxalates 14a-d were formed as the major products from 1,2-cyclopentane- and 1,2-cyclohexanediols regardless of the configuration. These results can be accounted for by assuming the boat-like transition states for cyclizations of the half esters of comparatively rigid five- and six-membered diols 9a--d. The cyclic oxalates 14a, c may be directly formed through the resulting tetrahedral intermediates from cis-diols (9a,c), and the cyclic carbonates 12a,c as the minor products after ring inversion of the tetrahedral intermediates. The tetrahedral intermediates from the trans-isomers 9b, d cannot undergo ring inversion, producing no traces of the cyclic carbonates 12b, d.     

Dynamics of the solvation of thallium 3,5-di-tert-butyl-o-semiquinolate by pyridine and triethylamine

The kinetic parameters were determined for forward and reverse solvation upon the interaction of thallium 3,5-di-tert-butyl-o-semiquinolate with pyridine and triethylamine. The solvation proceeds at almost the diffusion-controlled rate (k 10⁸–10⁹ liters/(mole·sec).Translated from Irvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 702–704, March, 1990.