Gas-chromatographic separation of aromatic amines, nitriles and hydrocarbons-I

A mixture of mono- and di-substituted nitriles was separated on six different liquid phases, but a mixture of mono- and di-substituted anilines was separated on only two liquid phases. The forces influencing the separation and elution order of these solutes are discussed. The absence of selective interactions between aromatic hydrocarbons and the various liquid phases was proved thermodynamically. An ortho methyl substituent increases the log of the specific retention volumes of the nitrile solutes by an approximately constant amount.     

Nitration of iron corrolates: further evidence for non-innocence of the corrole ligand

Mono- and di-substituted β-nitro derivatives have been obtained from the reaction of ttcorrFeCl with sodium nitrite in refluxing DMF. This result is unprecedented for iron corrolates and further evidences the non-innocent character of the corrole ligand.     

Reactivity of (3-chloro-2-methylenecycloalkyl)palladium chloride dimers: Nucleophilic attack by one or two equivalents of malonate anion.

The title compounds undergo reaction with one and two equivalents of malonate anion in the presence of phosphine ligands to afford mono- and di-substituted products. A mechanism for the formation of both products is presented.     

Substituent effects in mass spectrometry—II. The effect of substituents on the dissociation of para and meta disubstituted benzenes

The effect of substituents on the activation energy for primary dissociation processes in the molecular ions of mono- and para and meta di-substituted benzenes has been examined. Where the daughter ion retains the substituent group, variation of the energy of activation derives from a combination of the effects of substituents on the ionisation potential of the molecular ion and the appearance potential of the daughter ion. An equation relating the energy of activation for the fragmentation of the molecular ion of a mono-substituted benzene to that of related para and meta di-substituted benzenes is presented.     

Synthesis and evaluation of carbamate prodrugs of a phenolic compound

A series of carbamates of the phenolic compound 1 were prepared and evaluated in vivo as its prodrug. Each carbamate was orally administered to rats, and plasma concentrations of the parent compound 1 were measured with the passage of time. We judged which carbamate was suitable for the prodrug of 1 from both the AUC value of 1 and absence of the carbamate in plasma. The AUC value of 1 after oral administration of 2b was approximately 40-fold higher than that for an administration of 1, and the bioconversion from 2b to 1 was excellent. As a whole, di-substituted carbamates resulted in higher plasma concentrations of 1 than did mono-substituted ones. However di-substituted carbamates were almost always detected in plasma. As a result, we found that the ethycarbamoyl derivative 2b demonstrates the best prodrug property in this series.     

Synthesis and mesophase characterization of liquid crystalline polyesters with bulky,rigid, lateral substituents

The synthesis and characterization of aromatic polyesters containing various symmetrically di-substituted hydroquinone monomers is described. The homopolyesters made from these monomers and terephthalic acid (TA) did not melt. Copolyesters of TA with mono- and di-substituted hydroquinone formed liquid crystalline melts. Optical microscopy showed schlieren, marbled, and droplet textures characteristic of the nematic phase. DSC experiments were also in accord with mesophase formation as multiple transitions characteristic of first-order phase changes were found. In general, the crystal-nematic transition was about 300°C, whereas the nematic-isotropic change was over 400°C. All the polyesters were prone to decomposition near or above the isotropization temperature. © 1994 John Wiley & Sons, Inc.     

Oxidation of enamines to α-hydroxy ketones and α-amino ketones using N-sulfonyloxaziridines

Tri-substituted enamines are oxidized to α-hydroxy ketones by N-sulfonyloxaziridines while di-substituted enamines are oxidized to α-amino ketones. A unified mechanism for the formation of both α-hydroxy ketones and α-amino ketones is proposed.     

MMPP (Magnesium Monoperoxyphthalate) in Acetonitrile; A New Approach to the Synthesis of Lactones via Baeyer-Villiger Oxidation of Cyclic Ketones

A variety of unsubstituted and mono- or di-substituted cycloalkanones can be oxidised with modest excess of magnesium monoperoxyphthalate hexahydrate in acetonitrile to produce the corresponding lactones in a facile, selective, and high yielding manner.     

Palladium-catalyzed cross-coupling reaction of aryl trimethoxysilanes with terminal alkynes

A palladium-catalyzed cross-coupling reaction of aryl trimethoxysilanes with terminal alkynes was described. Thus, di-substituted alkynes were prepared in moderate to good yields. The electron-deficient terminal alkynes also worked well in the procedure.     

Palladium-catalyzed synthesis of substituted cyclopentadienes and indenes from allylic esters

Various mono- and di-substituted cyclopentadienes have been prepared by palladium-catalyzed alkylation of allylic esters with cyclopentadienide and t-butyl-cyclopentadienide anions. The same procedure has been applied to the preparation of substituted indenes.     

Recyclization of 5-carbethoxy-4-methyl-2-mercapto(amino,hydroxy) pyrimidines to give 5-acetyl-2-mercapto(amino,hydroxy)-4-hydroxypyrimidines

Conditions for the selective preparation of 5-carbethoxy-4-methyl-2-substituted pyrimidines or 5-acetyl-4-hydroxy-2-substituted pyrimidines by condensation of ethoxymethyleneacetoacetic ester with 1,3-binucleophiles are proposed. It is shown that under the influence of sodium ethoxide 5-carbethoxy-4-methyl-2-substituted pyrimidines undergo rearrangement to 5-acetyl-4-hydroxy-2-substituted pyrimidines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1558–1559, November, 1982.     

Allenes through Horner-Wadsworth-Emmons Olefination of Alkenylphosphonates

Mono- and di-substituted allenes 5 were synthesized by successive Horner-Wadsworth-Emmons olefination starting from methylene-bisphosphonate 1 and two carbonyl compounds. The key to success is KH or KH-18-crown-6 as a base for the second HWE olefination of hydroxyalkenylphosphonates 4 .     

Why is monoalkylation versus bis-alkylation of the Ni(II) complex of the Schiff base of (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide and glycine so selective? MP2 modelling and topological QTAIM analysis of chiral metallocomplex synthons of α-amino acids used for the preparation of radiopharmaceuticals for positron emission tomography

Chiral Ni(II) complexes are used for the preparation of carbon-11 or fluorine-18 enantiomerically pure α-amino acids for positron emission tomography (PET). They enable the selective monoalkylation of a glycine synthon with high stereoselectivity and the preparation of enantiomerically pure α-amino acids with quarternary α-carbon. Molecular modelling of non-, mono- and di-substituted complexes using quantum theory of atoms-in-molecule (QTAIM) topological analysis of electron density allowed us to formulate a new theory explaining the reasons for highly selective monomethylation of the complexes. In the non-substituted complex (GK), the α-carbon atom exhibits a higher atomic volume and a more positive charge in comparison with mono- and di-substituted complexes. This unusual behaviour is accompanied by increasing the bond critical point (BCP) ellipticity of the iminic bond in GK explained by the higher mechanical strain. Both phenomena indicate the increased reactivity and probably originate in more compact core of GK where shorter distances in the internal coordination sphere result in the higher strain of its bonds.     

Synthesis, computational modelling and liquid crystalline properties of some [3]ferrocenophane-containing Schiff’s bases and β-aminovinylketone: Molecular geometry-phase behaviour relationship

Rotationally fixed [3]ferrocenophane extends the variety of possible molecular geometries in its derivatives in comparison with unbridged ferrocenes. In this respect molecular geometry-liquid crystalline properties relationship studies in [3]ferrocenophane mesogens are of considerable interest. Different positional isomers of mono- and di-substituted [3]ferrocenophanes which are obtained by incorporating one or two promesogenic building blocks into the cyclopentadienyl rings are reported in this article. A series of mono-substituted [3]ferrocenophane-containing Schiff’s bases was synthesized by condensing isomeric p-aminophenyl [3]ferrocenophanes with appropriate aldehydes. Isomers of di-substituted [3]ferrocenophane amines gave rise to a series of azomethines with two promesogenic substituents in the cyclopentadienyl rings. Besides, a β-enaminoketone was prepared from 3-(p-aminophenyl)[3]ferrocenophane. Nematic and smectic mesophases were observed in the synthesized compounds under a polarizing optical microscope. The [3]ferrocenophane-containing β-enaminoketone showed complex mesomorphic behaviour connected with occurrence of the keto-enamine and imino-enol tautomeric equilibrium in this compound. On the base of computational models obtained by semi-empirical quantum chemistry calculations the molecular geometry-phase behaviour relationships were examined. It was demonstrated that mesomorphism of [3]ferocenophane azomethines depends on the spatial orientation of the substituents with respect to the propanediyl bridge in a case of mono-, and as well as to each other in a case of di-substituted derivatives.     

Pyrimidines

The reaction of methylenebisurea with 5-amino-1-R-pyrazoles and 3-ureido-1-phenylpyrazole gives 1- and 2-R-6-oxo-4,5,6,7-tetrahydropyrazolo[3,4-d]pyrimidines, respectively. The 1-R-6-oxo-4,5,6,7-tetrahydropyrazolo[3,4-d]pyrimidines are readily dehydrogenated to 1-R-6-hydroxypyrazolo[3,4-d]pyrimidines. The 2-R-6-oxo-4,5,6,7-tetrahydropyrazolo[3,4-d]pyrimidines could not be dehydrogenated.See [1] for communication XXXIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1696–1699, December, 1972.     

Dienecobalt tricarbonyl cations

Oxidation of dienedicarbonylcobalt dimers has yielded the novel dienetricarbonylcobalt cations, or, in presence of phosphine, the corresponding mono- and di-substituted salts.     

Selective reductive cleavage of 2-(phenylthio)pyrimidines for efficient synthesis of 2-(H)pyrimidines

A reaction method is described for selective reductive cleavage of 2-(phenylthio)pyrimidines using Pd(OAc)₂ and Et₃SiH to produce 2-(H)pyrimidines. The reaction proceeds efficiently with a wide range of 2-(phenylthio)pyrimidines. Considering the ready availability of 2-(arylthio)pyrimidines derived from oxidative CS cross coupling of 3,4-dihydropyrimidin-1H-2-thiones (DHPMs), this method unambiguously provides a shortcut to the preparation of 2-(H)pyrimidines with unprecedented diversity.     

Cobalt-catalyzed direct C–C bond formation between tetrahydrofuran and alkynes

We aimed to describe an efficient CoCl₂-catalyzed direct C–C bond formation of tetrahydrofuran (THF) with various alkynes in the presence of tert-butyl hydroperoxide and catalytic amount of acid to obtain vinyl-substituted THFs. Mono- and di-substituted alkynes were suitable for this transformation.     

The behaviour of some ferrocene derivatives under electron impact

The behaviour of some mono- and di-substituted ferrocene compounds under electron impact has been investigated by means of low-resolution mass spectrometry. Some characteristic rearrangement processes have been observed and discussed.     

Ring closure of cyclooctatetraenetricarbonyliron complexes: Crystal structure of a bicyclo[4.2.0]-2,4,7-octatrienetricarbonyliron compound

Mono- or di-substituted cyclooctatetraenetricarbonyliron complexes on heating yield isomeric bicyclo[4.2.0]-2,4,7-octátriene compounds; in contrast, the carbonylruthenium analogues afford polynuclear species.