C–F Bond Cleavage Reactions with Beryllium,Magnesium, Gallium,Hafnium, and Thorium Halides

The work describes unexpected stoichiometric C–F bond cleavage reactions of beryllium, magnesium, gallium, hafnium and thorium halides with α,α,α-trifluorotoluene. The reaction of BeBr₂ / GaBr₃ or MgBr₂ / GaBr₃ mixtures as well as neat GaI₃ with α,α,α-trifluorotoluene in the presence of (OSi₂Me₄)₂ ( I ) yields the carbenium ion containing compounds [Ph-C(O₂Si₂Me₄)][GaX₄] (X = Br: 1 , X = I/F: 2 ). Both compounds were successfully characterized and a defluorination type reaction under incorporation of a siloxy unit was observed. Compound 1 was also characterized by single-crystal X-ray diffraction analysis. The conversion of α,α,α-trifluorotoluene with BeI₂, HfI₄ or ThI₄ turned out to be a halodefluorination-type reaction with formation of α,α,α-triiodotoluene ( 3 ). An adequate NMR spectroscopic and the X-ray crystallographic characterization of 3 were performed for the first time.     

Reactions of 3-carene, limonene, and α-pinene nitrosochlorides with imidazole, benzotriazole, and indole

The reactions of terpene nitrosochlorides derived from 3-carene, ??-pinene, and limonene, with simplest azaheterocycles (imidazole, benzotriazole, and indole) were studied. On the base of these transformations, preparative procedures to access chiral oximes bearing azaheterocyclic moieties in the ??-position to the oxime fragment, namely, ??-(1H-imidazol-1-yl)-, ??-(1H-benzo-[d][1,2,3]triazol-1-yl)-, and ??-(1H-indol-3-yl)-substituted terpenic oximes, were developed. Transformations of the studied monoterpene nitrosochlorides into ??-substituted oximes proceeded stereoselectively to give in the moderate yields (30?C60%) the only stereoisomer arising from the attack of the heterocyclic anion from the less hindered side of the intermediate nitroso olefin generated in situ from nitrosochloride.     

Reactions of N,N′-diphenyl-p-quinonediimine with hydroquinone, α-tocopherol,and other antioxidants

Phenols (hydroquinone and -tocopherol) and heterocyclic aminophenols (2,2,4-trimethyl-6-ethoxy-1,2-dihyroquinoline) reduce N,N-diphenyl-p-quinonediimine (A) to the diamine. With difunctional hydrogen atom donors, the reaction rate is proportional to the concentrations of the reactants. The effective rate constants have been determined over a range of temperatures. In the reaction of A with -tocopherol, plots of rate versus initial concentrations are nonlinear, 2,6-Di-tert-butyl-4-methylphenol and 2,2,4-trimethyl-6-ethoxy-1,2-dihyroquinoline do not react with A under the same conditions.N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 417–420, February, 1992.     

Donor-acceptor interaction of p,p′-dimethoxystilbene with α,β-dinitrostilbene

A study was carried out on the interactions of the Z and E forms of the indicated stilbenes in all four possible combinations. Charge transfer complexes are formed and only Z-p,p-dimethoxystilbene converts to its E form.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 210–211, January, 1992.     

On study of chemoselectivity of reaction of trialkylalanes with alkenes, catalyzed with Zr π-complexes

The influence of the organoaluminium compound nature, Zr π-ligand environment, solvent type and reagent ratio on the chemoselectivity of reactions of trialkylalanes (AlMe₃, AlEt₃) with alkenes, catalyzed with L₂ZrCl₂ [L = Cp, Cp′ (Cp′-η⁵-C₅H₄CH₃), Cp^∗ (Cp^∗-η⁵-C₅(CH₃)₅), Ind (indenyl), Flu (fluorenyl)] has been studied. It is shown that in the case of AlMe₃, the hydro- and carboalumination products, and alkene dimers are formed. The catalytic reaction of AlEt₃ with the olefins yields aluminacyclopentanes altogether with the hydro- and carboalumination products, and the dimers. A probable reaction mechanism has been proposed.     

Reaction of α-cyanoacrylates with functionally substituted thiols,ethanedithiol, and hydrogen sulfide

Functionally substituted thiols, i.e., thioglycolic acid and cysteamine and cysteine hydrochlorides, facilely undergo addition at the double bond of -cyanoacrylates, forming the corresponding adducts in quantitative yields: RSCH₂CH(CN)COOR [R=CH₂COOH; CH₂CH₂NH₂·HCl; CH₂CH(COOH)NH₂·HCl]. Under similar conditions, the reaction with ethanedithiol gives the diadduct [CH₂SCH₂CH(CN)COOR]₂; the monoadduct HSCH₂CH₂SCH₂CH(CN)COOR is formed in a significantly lower yield. Hydrogen sulfide does not undergo addition to -cyanoacrylate in the absence of a catalyst; S[CH₂CH(CN)COOR]₂ is formed quantitatively in the presence of Et₃N. In the presence of triethylamine, this sulfide undergoes intramolecular cyclization (the Ziegler-Thorpe reaction) with formation of 4-amino-5-cyano-3,5-bis(ethoxycarbonyl)thiacyclohex-3-ene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2816–2820, December, 1991.     

Interactions of amphiphilic drugs withα-,β-, andγ-cyclodextrins

The association of several amphiphilic drugs with -, -, and -cyclodextrins has been measured by use of drug-sensitive electrodes. Drugs investigated are hydrochlorides of chlorpromazine, dibucaine, tetracaine, and procaine, and valethamate bromide. Each drug forms the drug:cyclodextrin=11 complex with - and -cyclodextrin, and both the 11 and 21 complex with -cyclodextrin, except valethamate which only forms the 11 complex. The strength of the 11 complex formations is in the order of CyD>-CyD>-CyD. The association constant of the 21 complex in drug--CyD is larger than that of 11 complex. The free energy change of the conplex formation has a positive correlation with that of the micelle formation of drugs. The deviation from this relation is explained in terms of fittability of the bulky hydrophobic group of drugs into the cyclodextrin's cavity. The free energy change for the complex formation between chlopromazine or valethamate and -CyD is governed by the enthalpy term and not by the entropy term which controls the surfactant--CyD interactions.     

Study on the Interaction of Rare Earth with 3, 5, 3''''-Triiodothyronine

HormoneisaveryhoP0tatkindofbiol0glcalmolede,ltplaTharegulationro1einmetabelism.TheinterachoLofrareeothwithborm0nehasearelybeenreporteds0far[1'2J.lntheprerentwork,theinteraedonofrareearthwith3.5,3'-triiodothryor`ire(T.)wasstodiaibyusingNMRandPOtentiometrictitrationat37tandanionicstrenotofO'15mo1e/LNaC1,TheP0tenhometrictitrah0nwasperformedin1:1DMSO-H.O(vol1imeratio)usingthemethoddedndinprevi01ispeper[3].TheNMR8peaofsarnples(PH=4,to)wererecorded'onBrukerARX-4ooNMRSpeCtrometerusingT…     

Reactions of cyclopentanone, γ-butyrolactone,and their derivatives with α-hydroxyethyl radicals

The interaction of cyclopentanone, 2-cyclopentenone, 1,3-cyclopentanedione, 3-methyl-1,2-cyclopentanedione, γ-butyrolactone, 2(5H)-furanone, ascorbic acid, and 5,6-O-isopropylidenyl-2,3-O-dimethylascorbic acid with α-hydroxyethyl radicals (α-HER) generated during the radiolysis of deaerated ethanol has been studied in the continuous irradiation mode. The test compounds, except γ-butyrolactone, oxidize α-HER. 2(5H)-Furanone and 2-cyclopentenone give hydroxyethylation products via the free-radical chain mechanism. In contrast to 2(5H)-furanone and 2-cyclopentenone, ascorbic and 5,6-O-isopropylidenyl-2,3-O-dimethyl-L-ascorbic acids are weaker oxidants for α-HER and attach these radicals at the multiple carbon-carbon bonds.     

Pt Complexes with High Molecular Weight Polyvinylmethyldimethylsiloxane Ligands Supported on Diatomite for Liquid-phase Hydrosilylation of 3, 3, 3-Trifluoropropene with Methyldichlorosilane

Hydrosilylation is one of the most important reactions for synthesis of modified siliane and polysiloxane. Since the discovery by Speier et al. in 1957 that hexachloroplatinic acid is a potent catalyst even under ambient conditions1, Pt complexes have bec…     

Reaction of 2-aminopyridines with α, β-unsaturated acids

The reaction of 2-amino- and 2-amino-5-halopyridines with acrylic, methacrylic, and crotonic acids forms N-(2-pyridyl)- and N-(5-halo-2-pyridyl)--alanines and the betaines 2-amino-1-(2-carboxylatoethyl)pyridinium or 3,4-dihydropyrido[1,2-a]pyrimidin-2-ones, or their homologs.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 80–85, January, 1992.     

Catalytic enantioselective conjugate additions with α,β-unsaturated sulfones

We describe the development of a highly efficient catalytic asymmetric conjugate addition to α,β-unsaturated sulfones. Utilizing practical bifunctional organic catalysts and involving air- and moisture-tolerant conditions, conjugate additions of a wide range of Michael donors to α,β-unsaturated sulfones proceeded in excellent enantioselectivity/diastereoselectivity and high yield. This efficient and operationally simple new catalytic asymmetric reaction should provide a versatile approach for the asymmetric synthesis of chiral sulfones bearing all-carbon quaternary stereocenters.     

Curing of N,N′-diglycidylimides with polyfunctional compounds

This paper describes the curing reactions of new N,N′-diglycidylimides containing trimellitimide units. Reactions were carried out using several polyfunctional curing agents, viz. aromatic primary diamines and phthalic anhydride. Spectroscopic techniques were used to study the curing process. The course of reaction was followed by i.r. spectroscopy. Some intermediate species were detected by recording ¹³C-NMR spectra until the products became insoluble in the usual deuterated solvents.     

Reaction of dibenzylphosphine oxide with α,β-unsaturated O-methyloximes

The reaction of dibenzylphosphine oxide with O-methyloximes of some ,-unsaturated ketones results in the phosphorylation at the -carbon atom to form methoxyiminophosphine oxides, whereas the reaction of dibenzylphosphine oxide with O-methyloximes of ,-unsaturated aldehydes affords aminodihydrophosphole oxides.