Synthesis and conversions of the dimer of 2-methylene-5,6-benzocyclohexan-1-one induced by H2S and acids

Reaction of 5, 6-benzocyclohexan-l-one with formaldehyde in the presence of bases gives the Diels—Alder dimer of the intermediate 2-methylene-5, 6-benzocyclohexan-l-one and the expectedmethylenebis-Sexpectedmethylenebis-5, 6-benzocyclohexan-l-one. The optimal conditions for the formation of the dimer and its conversion into the hydroxy-.1, 6-diketone are found. The reactions of these products with H₂S and acids are studied. The structures of the newly prepared compounds are confirmed by¹³C NMR.N. G. Chernyshevskii Saratov State University, Saratov 410026. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 898–901, July, 1994.     

Synthesis of 3-R2-4-R1-acetyl-(ethoxycarbonyl)-6-hydroxy-6-methylindazoles

It was discovered that functionally substituted tetrahydroindazoles can be aromatized by the action of sulfur. Previously unknown 3-R²-4-R¹-5-acetyl(ethoxycarbonyl)-6-methylindazoles were obtained. The products from aromatization cannot be obtained if a nitro group is introduced or one heteroatom in the substrate is replaced by oxygen.N. G. Chernyshevskii Saratov State University, Saratov, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 757–759, June, 1999.     

Effects of nickel catalyst composition on the rate and selectivity of carbon dioxide hydrogenation

The hydrogenation of carbon dioxide has been examined in relation to the activity of catalysts containing 1–10 wt.% nickel, particularly as affected by the method of making the catalyst. Studies have been done on how alkali additives affect the activity of a nickel-aluminum catalyst. Measurements have been done on thiophen poisoning in the hydrogenation of CO₂ on nickel catalysts. N. G. Chernyshevskii Saratov State University, Saratov State University Chemical Research Institute, 83 Astrakhanskaya ul., Saratov 410026, Russia. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 5, pp.311–316, September–October, 1999.     

Optimization of the geometry and electronic structure of bridged binuclear aromatic molecules

The geometries of the molecules of (C₆H₅)₂M, where M=NH, PH, O, S, CO, CS, SO, CH=CH, CH=N, N=N, and N=NO, the diphenylamine radical cation, and the diphenylnitrogen and diphenyl nitroxide radicals have been optimized by the CNDO/2, INDO, and MINDO/3 methods, and their electronic structures have been calculated. The data obtained have been interpreted in light of the investigation of the problem of reactivity.N. G. Chernyshevskii Saratov State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 2, pp. 23–29, March–April, 1991.     

Study of the mechanism of recyclization of furans into thiophenes and selenophenes in conditions of acid catalysis. 6. Experiments with labeled atoms. Quantum chemical calculations of intermediates of recyclization and hydrolysis

The reaction of 2-methyl-5-R-furans (R=Me, Bu, 2,2-pentyl-2-methylpentyl) with H₂ ¹⁸O was investigated. Furans and the corresponding 2,5-alkanediones containing the¹⁸O isotope were obtained. The general characteristics of the recyclization and isotope exchange reactions were established. A kinetic study of recyclization of 2,5-dimethylfuran with¹⁶O and¹⁸O into 2,5-dimethylthiophene was conducted. A reverse kinetic isotope effect was found. The schemes of the mechanisms of these processes were refined based on the experimental data and quantum-chemical calculations of the recyclization and hydrolysis intermediates.See [1] for Communication 5.Scientific-Research Institute of Chemistry, N. G. Chernyshevskii Saratov State University, Saratov 410026. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1035–1042, August, 1997.     

Herzberg-teller effect and intensity distribution in the absorption and raman scattering resonance spectra of polyatomic molecules

This paper studies the influence of the Herzberg-Teller effect on the intensity distribution in one- and two-photon absorption and Raman scattering resonance spectra of substituted benzenes. A quantum mechanical analysis of the intensity distribution in the spectra of phenylacetylene and pyrazine is accomplished using the general approach suggested in [1, 2]. Due to the inclusion of vibronic coupling in the calculation, one can explain the presence of lines (as well as their combinations and overtones) arising from one-quantum excitation of nontotally symmetric vibrations. The calculated data are in good agreement with the experimental data. Significantly, the two-photon absorption spectrum of pyrazine in the region of the¹A_1g→¹B_3u long-wave singlet-singlet transition is explained only by the Herzberg-Teller effect. Saratov State Pedagogical Institute. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 304–309, March–April, 1995. Translated by L. Smolina     

Deoxygenation of nitro and nitrosoaromatics by photolysis with t-BuHgl/Kl. Regiochemistry of tert-Butyl radical addition to nitrosoaromatics [1]

Photolysis of nitroaromatics in the presence of t-BuHgI/KI in Me₂SO or DMF leads to products formed by t-Bu^• addition to the nitroso compounds. Similar products are formed in the dark in the presence of K₂S₂O₈. Nitroso or nitrobenzene is converted into N,O-di-tert-butylphenylhydroxylamine by a process involving N-tert-butylphenylhydroxylamine as an intermediate. In the presence of PTSA and KI, N-tert-butylphenylhydroxylamine predominates in Me₂SO, but in DMF, the phenylhydroxylamine is reduced to N-tert-butylaniline. In a similar fashion, o-nitrosotoluene is converted into o-MeC₆H₄N(Bu-t)OBu-t, o-MeC₆H₄N(Bu-t)OH, and o-MeC₆H₄NHBu-t. p-Nitroso-N,N-dimethylaniline forms the N,O-di-tert-butylated derivative in the absence of acid but in the presence of PTSA/KI yields p-Me₂NC₆H₄NHBu-t. Excellent yields of the N,O-di-tert-butylated arylhydroxylamines are formed in DMF from the nitroaromatics with para Me₂N, OH, I, Br, Cl, and ortho Ph or PhNH substituents. Nitrobenzenes with p-CHO, p-PhCO, or p-CN substituents are deoxygenated to the nitroso compounds which react with t-Bu^• to form the tert-butoxyamino radicals (ArṄOBu-t). In Me₂SO, the amino radicals react to form ArN(HgI)OBu-t compounds which condense with the nitroso compounds to yield the azoxy compounds. With the p-CN substituent, the azoxy compound is subsequently deoxygenated and tert-butylated to yield p-NCC₆H₄N(Bu-t)NHC₆H₄CN-p. In the presence of PTSA/KI, the amino radicals are reduced to p-Y-ArNHOBu-t (Y = PhCO, CN). The compounds Y-ArN(Bu-t)OBu-t undergo photochemical degradation to yield Y-ArNHBu-t with Y = p-PhCO or p-CN in a reaction that is inhibited by I⁻. With PTSA/H₂O/KI in Me₂SO, p-Me₂NC₆H₄N(t-Bu)OBu-t is converted into 4-(N-tert-butylimino)-2,5-cyclohexadien-1-one, p-Me₂NC₆H₄NHBu-t, and p-tert-butylamino-m-tert-butoxy-N,N-dimethylaniline. o-MeC₆H₄N(Bu-t)OH reacts with PTSA/KI to form o-MeC₆H₄N(Bu-t)H in DMF or a mixture of the aniline and 4-(N-tert-butylimino)-3-methyl-2,5-cyclohexadien-1-one in Me₂SO. In the absence of KI, only the cyclohexadienone is formed in Me₂SO.     

Synthesis,structure, and 77Se NMR study of the (PPh4)2[Re6Se6Br8] complex

The octahedral cluster anion [Re₆Se₆Br₈]^2– was prepared by high-temperature synthesis from elementary substances in the presence of KBr. This cluster anion was isolated and structurally characterized by single-crystal X-ray diffraction analysis as the (PPh₄)₂[Re₆Se₆Br₈] complex (1). Refluxing of polymeric rhenium selenide bromide Re₆Se₆Br₆ in DMF in the presence of Bu₄NBr led to the cleavage of the Re—Br—Re bridges to form the complex (Bu₄N)₂[Re₆Se₆Br₈]. Comparative analysis of the interatomic distances in the octahedral rhenium(iii) selenide bromide clusters was carried out.     

Atranes

Silatrane, in the presence of the corresponding sodium alkoxide of phenoxide readily reacts with alcohols and phenols with the liberation of hydrogen and the formation of 1-alkoxy- or 1-aryloxyatranes, . Depending on the nature of the alcohol or phenol, the rate of the reaction falls in the following sequence: p-CH₃OC₆H₄OH > p-(CH₃)₃CC₆H₄OH = n-C₄H₉OH = = n-C₅H₁₁OH > i-C₄H₉OH > s-C₄H₉OH > p-CH₃C₆H₄OH > C₆H₅OH > > p-ClC₆H₄OH > t-C₄H₉OH > p-O₂NC₆H₄OH > C₆F₅OH. The rate of the dehydrocondensation reaction of hydrosilanes with alcohols rises in the sequence . In the presence of ZnCl₂ as catalyst, the dehydrocondensation reaction of silatrane with alcohols takes place considerably more slowly and does not go to completion. The formation of 1-organyloxysilatranes from silatrane and alcohols does not take place in the presence of H₂PtCl₆ or in the absence of catalysts. Using the dehydrocondensation reaction, twelve 1-organyloxysilatranes have been synthesized, two of which were previously unknown.     

Determination of flunixin by sensitized terbium fluorescence in the presence of surfactant micelles

The effect of surfactant micelles and the second ligand on the efficiency of energy transfer in the Tb³⁺–flunixin complex was studied. The fluorescence intensity of the Tb³⁺–flunixin complex was shown to 100-fold increase in the presence of Tween 80 micelles and the second trioctylphosphine oxide ligand. A procedure for the fluorimetric determination of flunixin in the Flunex drug product (NITA-FARM, Saratov, Russia) was developed. The linearity range of the calibration curve was from 1 × 10^–7 to 1 × 10^–4 M, r ² = 0.991, and the limit of detection was 4 × 10^–8 M (3σ).     

Esterification in dry Media Using Ferric Perchlorate Adsorbed on Silica Gel

Adsorption of Fe(ClO₄)₃(H₂O)₆ onto chromatographic grade silica gel in the presence of alcohol (to be used for esterification) produces a supported reagent, Fe(ClO₄)₃(ROH)₆/SiO₂. This reagent, has been found effective for the rapid and high yield of esters, on grinding in the presence of carboxylic acids using pestle and mortar in the solid state.     

Darstellung und kristallographische Daten von Tetracalciumplatinoxid Ca4PtO6

On synthesising Ca-silicates from a CaCl₂-flux in the presence of Platinum, Ca₄PtO₆ was found. The compound crystallises orthorhombic (see ?Inhaltsübersicht”?). Relations to Sr₄PtO₆ are described.     

Synthesis,characterization, and electrochemistry of monophosphine‐containing diiron propane‐1,2‐dithiolate complexes related to the active site of [FeFe]‐hydrogenases

Five monophosphine‐substituted diiron propane‐1,2‐dithiolate complexes as the active site models of [FeFe]‐hydrogenases have been synthesized and characterized. Reactions of complex [Fe₂(CO)₆{μ‐SCH₂CH(CH₃)S}] ( 1 ) with a monophosphine ligand tris(4‐methylphenyl)phosphine, diphenyl‐2‐pyridylphosphine, tris(4‐chlorophenyl)phosphine, triphenylphosphine, or tris(4‐fluorophenyl)phosphine in the presence of the oxidative agent Me₃NO·2H₂O gave the monophosphine‐substituted diiron complexes [Fe₂(CO)₅(L){μ‐SCH₂CH(CH₃)S}] [L = P(4‐C₆H₄CH₃)₃, 2 ; Ph₂P(2‐C₅H₄N), 3 ; P(4‐C₆H₄Cl)₃, 4 ; PPh₃, 5 ; P(4‐C₆H₄F)₃, 6 ] in 81%–94% yields. Complexes 2 – 6 have been characterized by elemental analysis, spectroscopy, and X‐ray crystallography. In addition, electrochemical studies revealed that these complexes can catalyze the reduction of protons to H₂ in the presence of HOAc.     

Synthesis of polyfluoroaromatic ketones from polyfluoroarylzinc compounds and acyl chlorides in the presence of CuCl

Polyfluoroaromatic ketones Ar_FCOAlk and Ar_FCOPh (Ar_F = C₆F₅, 3- and 4-F₃CC₆F₄, 4-NCC₆F₄, 4-EtOCOC₆F₄, C₅F₄N, nonafluoroindan-5-yl; Alk = Me, Et, i-Pr, t-Bu) were synthesized by reactions of polyfluoroarylzinc compounds with acyl chlorides in the presence of CuCl.     

Chemistry of 2-mercaptophenol (H2mp) . Part iii. One dimensional arrays of binuclear anions of Mo (VI) linked by bis (2-hydroxyphenyl) disulfide via hydrogen bondings

The reaction of (Bu₄N) ₄ [Mo₈O₂₆] with a suitable amount of 2-mercaptophenol (H₂mp) in MeOH in the presence of equimolar Et₃N gave the complex (Bu₄N) ₂ [{MoO₂ (2-SC₆H₄O) }₂ (μ-O) ] (2 2′-HOC₆H₄SSC₆H₄OH) 2H₂O (1) with a one-dimensional chain network formed via hydrogen bondings (average OH OMo distance 2655 Å) of the hydroxyl groups in the spacer 2 2′-HOC₆H₄SSC₆H₄OH with the terminal oxo groups of the dimolybdenum anions 2 2′-HOC₆H₄SSC₆H₄OH was obtained by oxidation of H₂mp in the presence of molybdenum when the reaction was run in air The characteristic cis-MoO₂² absorptions appear at 913 and 864 cm^{−1 1} H NMR and ¹ H–¹ H COSY spectra characterized the phenyl protons of the mercaptophenol groups in the anion and in 22′-HOC₆H₄SSC₆H₄OH in the ranges of 6700–6270 and 7368–6799 ppmrespectivelywith ³J and ⁴J coupling constants of 8 and 1 Hz respectively.     

A comparative screening of the catalytic activity of nanocrystalline M<Superscript>II</Superscript>Zr<Subscript>4</Subscript>(PO<Subscript>4</Subscript>)<Subscript>6</Subscript> ceramics in the one-pot synthesis of 1,6-diamino-4-aryl-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile derivatives

A four-component reaction of hydrazine hydrate, ethyl cyanoacetate, malononitrile, and aromatic aldehydes was achieved in the presence of nanocrystalline M^IIZr₄(PO₄)₆ ceramics (M^II: Mn, Fe, Co, Ni, Cu, Zn, Cd) as heterogeneous catalysts to produce N-amino-2-pyridones. The reactions were performed in the presence of different catalysts, and it is observed that CdZr₄(PO₄)₆ nanocrystallines are the best catalysts among those examined. Atom economy, excellent yields in short times, high catalytic activity, recycling of catalyst, and environmental benignity are some of the important features of this protocol.     

Synthesis and X‐ray crystal structures of hypervalent arsenic compounds bearing arsenic‐iron bonds

A hypervalent arsorane with an As–Fe bond [ 6 : Rf₂As*FeCp(CO)₂ (Rf: o‐C₆H₄C(CF₃)₂O‐)] was synthesized by the reaction of the arsoranide anion ( 4‐Et ₄N: Rf₂As*^‐Et₄N⁺) with CpFe(CO)₂I ( 5 ) in the presence of AgBF₄. Diastereomeric arsoranes { 7a and 7b : Rf₂As*Fe*Cp(CO)(PPh₃)} were prepared by irradiation of 6 with a tungsten lamp in the presence of triphenylphosphine. X‐ray crystallographic analysis of 6 and 7a showed that the apical As–O bond lengths of these compounds are slightly longer than the equatorial As–C bonds. It is concluded that an electron‐donating group at the equatorial position elongates the apical E–O bond by electron donation to the apical oxygens. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:42–47, 2000     

Si44– in Solution – First Solvate Crystal Structure of the Ligand‐free Tetrasilicide Tetraanion in Rb1.2K2.8Si4·7NH3

We report the first solvate structure of the silicide anion Si₄^4–, which provides circumstantial evidence of the stability of the highly charged anion in liquid ammonia solutions. The solvate Rb_1.2K_2.8Si₄ · 7NH₃ crystallized from a mixture of the ternary compound K₆Rb₆Si₁₇ with the transition metal complex [(C₆H₅)₃P]₂Ni(CO)₂ [bis(triphenylphosphine)dicarbonylnickel] in the presence of the chelating agents 18‐crown‐6 (1,4,7,10,13,16‐hexaoxacyclooctadecane) and [2.2.2]cryptand (4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane) in liquid ammonia. Single X‐ray diffraction analysis confirms the presence of the Si₄^4– anion in the crystal structure of Rb_1.2K_2.8Si₄ · 7NH₃, which represents the first solvate compound of the naked tetrasilicide tetraanion. All five crystallographically independent cation positions show mixed occupancy by Rb⁺ and K⁺.     

Synthesis and characterisation of cyclo-boratetrasiloxane, (RBO)(Me2SiO)3 (R=nBu,Ar), derivatives

Low temperature reactions of dilute solutions of 1,5-dichloro-1,1,3,3,5,5-hexamethyltrisiloxane with boronic acids {RB(OH)₂; R=ⁿBu, C₆H₄Me-2, C₆H₄Me-3, C₆H₄Me-4, C₆H₄OMe-3, C₆H₄OMe-4, C₆H₄Br-2, C₆H₄Br-3, C₆H₄Br-4} in the presence of a twofold excess of Et₃N afforded the 8-membered ring products, cyclo-boratetrasiloxanes, (RBO)(Me₂SiO)₃, in moderate yields. New compounds were colourless oils and were characterised by elemental analysis, NMR (¹H, ¹¹B, ¹³C, ²⁹Si), IR and MS. The cyclo-boratetrasiloxanes are weakly Lewis acidic, with acceptor number (AN) values of ∼30, but do not form adducts with amines.     

4-Ferrocenylpyridine- and 4-Ferrocenyl-3-ferrocenylmethyl-3,4-dihydropyridine-3,5-dicarbonitriles: Multi-Component Synthesis, Structures and Electrochemistry

The reactions of 2-cyano-3-ferrocenylacrylonitrile (1) with malononitrile (2) in a MeOH/H₂O or 2-PrOH/H₂O medium in the presence of Na₂CO₃ afforded 6-alkoxy-2-amino-4-ferrocenylpyridine-3,5-dicarbonitriles 3a,b (multi-component condensation) and 6-alkoxy-2-amino-4-ferrocenyl-3-ferrocenylmethyl-3,4-dihydropyridine-3,5-dicarbonitriles 4a,b (multi-component cyclodimerization). Analogous reactions of 1 with 2 in an MeOH/H₂O medium in the presence of NaOH, piperidine, or morpholine gave compounds 3a, 4a and 2-amino-4-ferrocenyl-6-hydroxy-, 6-piperidino- and 6-morpholinopyridine-3,5-dicarbonitriles 3c-e, respectively. The structures of the compounds 3b, 4a and 4b were established by the spectroscopic data and X-ray diffraction analysis. The electrochemical behaviour of compounds 3b, 3d and 4b was investigated by means of cyclic voltammetry.