Reactions of 2-phenylpyrrole with bromobenzoylacetylene on metal oxides active surfaces

The solvent-free interaction of 2-phenylpyrrole with bromobenzoylacetylene (room temperature) upon their grinding with solid metal oxides (MgO, CaO, ZnO, BaO, Al₂O₃, TiO₂, ZrO₂) and salts (CaCO₃, ZrSiO₄) leads to either the cross-coupling product or the adduct of pyrrole addition to the riple bond of acetylene. The ethynylation is accompanied by the formation of intermediate and side products: E-2-(1-bromo-2-benzoylethenyl)-5-phenylpyrrole and 1,1-di(5-phenylpyrrol-2-yl)-2-benzoylethene. The activity of the metal oxides in the ethynylation reaction falls in the order (in the brackets, the content of 2-benzoylethynyl-5-phenylpyrrole in the reaction mixture is given): ZnO (81%), BaO (73%), Al₂O₃ (71%), MgO (69%), CaO (50%). The oxides, SiO₂, TiO₂, ZrO₂, and the salts, CaCO₃ and ZrSiO₄, are inactive in the ethynylation reaction affording only the intermediate adduct, with ZrO₂ the isolated yield of the bromoethenylpyrrole reaching 60%. ESR monitoring shows the reaction to start from one electron transfer from pyrrole to acetylene mediated by the oxide surface. The adduct is readily converted on Al₂O₃ to 2-(benzoylethynyl)-5-phenylpyrrole crystallized mostly as cis-rotamer (X-ray data).     

Copolymerization of N-Vinyl-4,5,6,7-tetrahydroindole with Acrylamide

Radical copolymerization of N-vinyl-4,5,6,7-tetrahydroindole with acrylamide in dimethylformamide was studied, and the relative activity constants of the monomers were determined.     

Reactions of 1-vinyl-4,5,6,7-tetrahydroindole and its mixtures with 4,5,6,7-tetrahydroindole in the presence of Cr- and Pd-coated catalysts

In the presence of Cr- and Pd-coated -alumina catalysts, 1-vinyl-4,5,6,7-tetrahydroindole (VTHI) and its mixtures with 4,5,6,7-tetrahydroindole (THI) are converted into 1-ethyl-4,5,6,7-tetrahydroindole (1-ETHI), indole, and 2-ethylindole, in proportions dependent on the reaction conditions and the catalyst. Over a sulfided 1% Pd--alumina catalyst in the presence of hydrogen at 200°C, VTHI is converted into 1-ETHI and THI. When the temperature is raised to 300–350°C, indole is formed in addition to these products. A 11 mixture of VTHI and THI over 1% Pd--alumina at 300°C gives indole and 2-ethylindole, over a sulfided 1% Pd --alumina catalyst at 200°C, 1-ETHI, and over a Cr oxide catalyst at 500°C, indole.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1417–1422, June, 1991.     

Reaction of N-acyl salts of heteroaromatic cations with 4,5,6,7-tetrahydroindole — A possible pathway to 2-heterylindoles

The reaction 4,5,6,7-tetrahydroindole with various N-heteroaromatic bases in the presence of acyl halides proceeds via a mechanism involving hetarylation and leads to corresponding 2-substituted 4,5,6,7-tétrahydroindoles. The structures of the compounds obtained were confirmed by data from the IR, mass, and PMR spectra.Translated from Khimiya Geterotsikli-cheskikh Soedinenii, No. 2, pp. 167–169, February, 1978.     

Free-radical cooligomerization of N-vinyl-4,5,6,7-tetrahydroindole with butyl vinyl ether

Oligo(N-vinyl-4,5,6,7-tetrahydroindole-co-butyl vinyl ethers) have been synthesized through free-radical cooligomerization with a yield of 84%. The copolymers are readily soluble in organic solvents (benzene, 1,4-dioxane, chloroform, and tetrahydrofuran), stable up to 380–400°C, and paramagnetic. (The concentration of paramagnetic centers is 10¹⁴ spin/g.) In addition, the copolymers exhibit the properties of organic semiconductors. (After being doped with iodine, σ = 1.1 × 10^?7 S/cm.) The analysis of the ¹H and ¹³C NMR spectra has shown that the oligomerization reaction is complicated by intramolecular cyclization involving carbon atoms located at the 2-position of pyrrole rings.     

Synthesis and mass spectrometry of 4-oxo-4,5,6,7-tetrahydroindole and 4-oxo-4,5,6,7-tetrahydrobenzofuran derivatives

We describe in this communication the synthesis and mass spectrometry of some l-aryl-2-phenyl-4-oxo-4,5,6,7-tetrahydroindole (IIIb, IVab-VIIIab, VIIIb, IXb) and 2-phenyl-4-oxo-4,5,6,7-tetrahydrobenzofuran derivatives (IIab). The fragmentations of these compounds are characterized by selectivity and the absence of any primary fragmentations involving substituents of the aryl rings. It is suggested that positive charges of the molecular ions of compounds II? IX are localized in the region of the carbonyl group and the conjugated double bond of the heterocycle.     

Immobilization of nanofibrous metal oxides on microfibers: a macrostructured catalyst system functionalized with nanoscale fibrous metal oxides

Nanofibrous LaMnO(3) can be immobilized on macrostructured materials using carbon nanofibers as templates; their application as macro-nanostructured catalysts are also presented.     

Condensation of 2-amino-3-cyano-4,5,6,7-tetrahydroindole with Β-dicarbonyl compounds

Depending on conditions, the condensation of 2-amino-3-cyano-4,5,6,7-tetrahydroindole with -dicarbonyl compounds leads to 2-methyl-4-oxo- or 4-methyl-2-oxo-10-cyano-6,7,8,9-tetrahydropyrimido[1,2-a]indoles via the intermediate compounds: 2-(3-ethoxy-carbonyl-prop-2-en-2-yl amino) and 2-(1,3-dioxobutylamino)-3-cyano-4,5,6,7-tetrahydroindoles, respectively.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 833–838. June, 1989.     

Electrical conductivity of copolymers of 1-vinyl-1,2,4-triazole with N-vinyl-4,5,6,7-tetrahydroindole

New copolymers of 1-vinyl-1,2,4-triazole with N-vinyl-4,5,6,7-tetrahydroindole of different compositions were synthesized. The processes of doping them with diiodine and electrophysical properties were studied. An increase in the electrical conductivity of the diiodinedoped copolymers by seven orders of magnitude due to the formation of charge-transfer complexes was observed.     

Atomic layer deposition of metal oxides on pristine and functionalized graphene

We investigate atomic layer deposition (ALD) of metal oxide on pristine and functionalized graphene. On pristine graphene, ALD coating can only actively grow on edges and defect sites, where dangling bonds or surface groups react with ALD precursors. This affords a simple method to decorate and probe single defect sites in graphene planes. We used perylene tetracarboxylic acid (PTCA) to functionalize the graphene surface and selectively introduced densely packed surface groups on graphene. Uniform ultrathin ALD coating on PTCA graphene was achieved over a large area. The functionalization method could be used to integrate ultrathin high-kappa dielectrics in future graphene electronics.     

Copolymerization of vinyl chloride with 1-vinyl-4,5,6,7-tetrahydroindole and 2-methyl-5-vinylpyridine

The radical copolymerization of vinyl chloride with 2-methyl-5-vinylpyridine and 1-vinyl-4,5,6,7-tetrahydroindole is accompanied by dehydrochlorination. In the vinyl chloride-2-methyl-5-vinylpyridine system, the evolved hydrogen chloride interacts with a pyridine hydrogen atom to give charged units of a heterocycle. In the vinyl chloride-1-vinyl-4,5,6,7-tetrahydroindole system, the hydrogen chloride being formed initiates the cationic dimerization of a nitrogen-containing monomer. The synthesized copolymers based on vinyl chloride surpass the commercial poly(vinyl chloride) in terms of thermal stability and solubility in organic solvents.     

Cross-coupling of aromatic bromides with allylic silanolate salts

The sodium salts of allyldimethylsilanol and 2-butenyldimethylsilanol undergo palladium-catalyzed cross-coupling with a wide variety of aryl bromides to afford allylated and crotylated arenes. The coupling of both silanolates required extensive optimization to deliver the expected products in high yields. The reaction of the allyldimethylsilanolate takes place at 85 degrees C in 1,2-dimethoxyethane with allylpalladium chloride dimer (2.5 mol %) to afford 73-95% yields of the allylation products. Both electron-rich and sterically hindered bromides reacted smoothly, whereas electron-poor bromides cross-coupled in poor yield because of a secondary isomerization to the 1-propenyl isomer (and subsequent polymerization). The 2-butenyldimethylsilanolate (E/Z, 80:20) required additional optimization to maximize the formation of the branched (gamma-substitution) product. A remarkable influence of added alkenes (dibenzylideneacetone and norbornadiene) led to good selectivities for electron-rich and electron-poor bromides in 40-83% yields. However, bromides containing coordinating groups (particularly in the ortho position) gave lower, and in one case even reversed, selectivity. Configurationally homogeneous (E)-silanolates gave slightly higher gamma-selectivity than the pure (Z)-silanolates. A unified mechanistic picture involving initial gamma-transmetalation followed by direct reductive elimination or sigma-pi isomerization can rationalize all of the observed trends.     

One-electron transfer in the vinylation of 4,5,6,7-tetrahydroindole with acetylenes in the system KOH-DMSO

It has been shown by EPR, using 2-methyl-2-nitrosopropane as a radical trap, that vinylation of 4,5,6,7-tetrahydroindole with phenylacetylene in the system KOH-DMSO involves the formation of the 4,5,6,7-tetrahydroindolyl radical by transfer of an electron from the 4,5,6,7-tetrahydroindole anion to the acetylene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 142–144, January, 1990.     

Hydroxyalkylation of 4,5,6,7-tetrahydroindole with polyfluorocarbonyl compounds as a route to 2-substituted indoles

The regioselective hydroxyalkylation of 4,5,6,7-tetrahydroindole at position 2 using highly electrophilic polyfluorocarbonyl compounds was performed for the first time. Oxidation of the products thus formed leads to indoles having 2-hydroxypolyfluoroalkyl and polyfluoroacyl groups.     

Synthesis and characterization of diazonium functionalized nanoparticles for deposition on metal surfaces

Silica nanoparticles were surface-functionalized with diazonium groups. The reaction steps leading to the formation of the diazonium functionality were followed with IR and XPS, and the structure of the diazonium-functionalized nanoparticle was confirmed with solid state NMR. Nanoparticle size distribution was determined with DLS, SEM, and TEM. The nanoparticles were then covalently bonded to gold and iron surfaces. Their spatial distribution over the metal surface was analyzed by SEM. Diazonium modification of nanoparticles represents a new method for the covalent attachment of nanoparticles to metal surfaces.     

Copolymerization of 1-Vinyl-4,5,6,7-tetrahydroindole with Vinyl Chloride in the Presence of a Radical Initiator

Copolymerization of 1-vinyl-4,5,6,7-tetrahydroindole with vinyl chloride in the presence of azobis(isobutyronitrile) occurs as a two-step process. The copolymer is initially formed by the radical mechanism. Then, the eliminated hydrogen chloride initiates cationic oligomerization of 1-vinyl-4,5,6,7-tetrahydroindole, enriching the copolymer with units of this monomer.     

A preparative synthesis of indole by dehydrogenation of 4,5,6,7-tetrahydroindole over catalysts with a low palladium content

Catalysts containing 0.15–0.5 % of Pd are highly active and selective in the dehydrogenation of 4,5,6,7-tetrahydroindole to indole when γ-Al₂O₃ or Sibunite are used as supports. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1832–1833, October, 1993.