- Symmetry-breaking intramolecular charge transfer in the excited state of meso-linked BODIPY dyads
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We report the synthesis and characterization of symmetric BODIPY dyads where the chromophores are attached at the meso position, using either a phenylene bridge or direct linkage. Both molecules undergo symmetry-breaking intramolecular charge transfer in the excited state, and the directly linked dyad serves as a visible-light-absorbing analogue of 9,9′-bianthryl.
- Whited, Matthew T.,Patel, Niral M.,Roberts, Sean T.,Allen, Kathryn,Djurovich, Peter I.,Bradforth, Stephen E.,Thompson, Mark E.
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Read Online
- Mechanisms of the Au- and Pt-catalyzed intramolecular acetylenic schmidt reactions: A DFT study
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The reaction mechanisms of the PtCl4- and Au(I)-catalyzed intramolecular acetylenic Schmidt reactions were analyzed by means of hybrid density functional calculations at the B3LYP/6-31G*(LANL2DZ) level of theory for better understanding of the
- Xia, Yuanzhi,Huang, Genping
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Read Online
- Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
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Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
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supporting information
p. 9029 - 9039
(2021/06/28)
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- Neutrophil-Selective Fluorescent Probe Development through Metabolism-Oriented Live-Cell Distinction
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Human neutrophils are the most abundant leukocytes and have been considered as the first line of defence in the innate immune system. Selective imaging of live neutrophils will facilitate the in situ study of neutrophils in infection or inflammation events as well as clinical diagnosis. However, small-molecule-based probes for the discrimination of live neutrophils among different granulocytes in human blood have yet to be reported. Herein, we report the first fluorescent probe NeutropG for the specific distinction and imaging of active neutrophils. The selective staining mechanism of NeutropG is elucidated as metabolism-oriented live-cell distinction (MOLD) through lipid droplet biogenesis with the help of ACSL and DGAT. Finally, NeutropG is applied to accurately quantify neutrophil levels in fresh blood samples by showing a high correlation with the current clinical method.
- Gao, Min,Lee, Sun Hyeok,Park, Sang Hyuk,Ciaramicoli, Larissa Miasiro,Kwon, Haw-Young,Cho, Heewon,Jeong, Joseph,Chang, Young-Tae
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supporting information
p. 23743 - 23749
(2021/10/14)
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- Thermal Behavior Analysis of Two Synthesized Flavor Precursors of N-alkylpyrrole Derivatives
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To expand the library of pyrrole-containing flavor precursors, two new flavor precursors—methyl N-benzyl-2-methyl-5-formylpyrrole-3-carboxylate (NBMF) and methyl N-butyl-2-methyl-5-formylpyrrole-3-carboxylate (NUMF)—were synthesized by cyclization, oxidation, and alkylation reactions. Thermogravimetry (TG), differential scanning calorimeter, and pyrolysis–gas chromatography/mass spectrometry were utilized to analyze the thermal degradation behavior and thermal degradation products of NBMF and NUMF. The TG-DTG curve indicated that the maximum mass loss rates of NBMF and NUMF appear at 310 and 268°C, respectively. The largest peaks of NBMF and NUMF showed by the differential scanning calorimeter curve were 315 and 274°C, respectively. Pyrolysis–gas chromatography/mass spectrometry detected small molecule fragrance compounds appeared during thermal degradation, such as 2-methylpyrrole, 1-methylpyrrole-2-carboxylic acid methyl ester, limonene, and methyl formate. Finally, the thermal degradation mechanism of NBMF and NUMF was discussed, which provided a theoretical basis for their application in tobacco flavoring additives.
- Ai, Lvye,Liu, Mengzhen,Ji, Xiaoming,Lai, Miao,Zhao, Mingqin,Ren, Tianbao
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p. 2389 - 2397
(2019/08/01)
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- Synthesis, electrochemical/photophysical properties and computational investigation of 3,5-dialkyl BODIPY fluorophores
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A series of 3,5 dimethyl and diethyl BODIPY with different substitutions at meso position are synthesized and characterized. Photophysical and electrochemical features of the 3,5 dialkyl BODIPY fluorophores are investigated using experimental and computational approaches. All fluorophores display absorption maxima around at 510 nm and emission maxima around at 520 nm which correspound to very narrow Stokes shift. Among the fluorophores, 3,5,8 alkylated BODIPYs are found to have high fluorescence quantum yield (1.00–0.93). 4-Bromophenyl group at meso position decreases fluorescence quantum yield of the dye while it increases with 4-methoxyphenyl group at meso position. The HOMO-LUMO energies of synthesized fluorophore compounds were calculated by B3LYP/6-31G(d,p) and B3LYP/6-311+G(d,p) levels in chloroform phase. Electron donating and accepting groups show increasing and decreasing effect on the band gaps of the fluorophores respectively.
- Derin, Yavuz,Y?lmaz, Ra?it Fikret,Baydilek, ?brahim Halil,Atalay, Vildan Eniso?lu,?zdemir, Abdil,Tutar, Ahmet
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p. 130 - 135
(2018/06/14)
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- A General Copper Catalyst for Photoredox Transformations of Organic Halides
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A broadly applicable copper catalyst for photoredox transformations of organic halides is reported. Upon visible light irradiation in the presence of catalytic amounts of [(DPEphos)(bcp)Cu]PF6 and an amine, a range of unactivated aryl and alkyl halides were shown to be smoothly activated through a rare Cu(I)/Cu(I)?/Cu(0) catalytic cycle. This complex efficiently catalyzes a series of radical processes, including reductions, cyclizations, and direct arylation of arenes.
- Michelet, Bastien,Deldaele, Christopher,Kajouj, Sofia,Moucheron, Cécile,Evano, Gwilherm
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supporting information
p. 3576 - 3579
(2017/07/17)
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- BACKGROUND-FREE FLUORESCENT PROBES FOR LIVE CELL IMAGING
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BODIPY (boron-dipyrromethene) containing fluorescent compounds for use in live cell intracellular imaging are described. Methods of producing the compounds, methods of labeling tagged organelles, and methods of live cell intracellular imaging using the compounds/probes are described herein.
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Page/Page column 25
(2017/06/24)
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- Transition-Metal-Free CO-Releasing BODIPY Derivatives Activatable by Visible to NIR Light as Promising Bioactive Molecules
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Carbon monoxide-releasing molecules (CORMs) are chemical agents used to administer CO as an endogenous, biologically active molecule. A precise spatial and temporal control over the CO release is the major requirement for their applications. Here, we report the synthesis and properties of a new generation of transition-metal-free carbon monoxide-releasing molecules based on BODIPY chromophores (COR-BDPs) activatable by visible-to-NIR (up to 730 nm) light. We demonstrate their performance for both in vitro and in vivo experimental settings, and we propose the mechanism of the CO release based on steady-state and transient spectroscopy experiments and quantum chemical calculations.
- Palao, Eduardo,Slanina, Tomá?,Muchová, Lucie,?olomek, Tomá?,Vítek, Libor,Klán, Petr
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p. 126 - 133
(2016/01/25)
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- Expedient one-pot synthesis of pyrroles from ketones, hydroxylamine, and 1,2-dichloroethane
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2- and 2,3-Substituted pyrroles are readily synthesized in a one-pot procedure from ketones, hydroxylamine hydrochloride, and 1,2-dichloroethane in the KOH/DMSO system (120 °C, 2-4 h), the yields of pyrroles ranging 11-85%. Aliphatic, cycloaliphatic, aromatic, and heteroaromatic ketones tolerate the reaction conditions.
- Trofimov, Boris A.,Mikhaleva, Al'Bina I.,Ivanov, Andrei V.,Shcherbakova, Viktoria S.,Ushakov, Igor A.
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p. 124 - 128
(2015/02/02)
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- Organocatalytic enantioselective multicomponent synthesis of pyrrolopiperazines
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The first organocatalytic multicomponent synthesis of enantioenriched pyrrolopiperazines is reported. These biologically relevant fused tricyclic products were obtained under catalytic iminium activation through a reaction sequence involving an enantioselective Michael addition followed by an iminium ion trapping via Pictet-Spengler cyclization (MAPS sequence). Substantial possibilities for variation on the three reaction partners [β-keto ester, enal and N-(2-aminoethyl)pyrrole] along with excellent enantioselectivities are the highlights of the present transformation.
- Du, Haiying,Rodriguez, Jean,Bugaut, Xavier,Constantieux, Thierry
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supporting information
p. 851 - 856
(2014/04/03)
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- Molecular products from the thermal degradation of glutamic acid
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The thermal behavior of glutamic acid was investigated in N2 and 4% O2 in N2 under flow reactor conditions at a constant residence time of 0.2 s, within a total pyrolysis time of 3 min at 1 atm. The identification of the main pyrolysis products has been reported. Accordingly, the principal products for pyrolysis in order of decreasing abundance were succinimide, pyrrole, acetonitrile, and 2-pyrrolidone. For oxidative pyrolysis, the main products were succinimide, propiolactone, ethanol, and hydrogen cyanide. Whereas benzene, toluene, and a few low molecular weight hydrocarbons (propene, propane, 1-butene, and 2-butene) were detected during pyrolysis, no polycyclic aromatic hydrocarbons (PAHs) were detected. Oxidative pyrolysis yielded low molecular weight hydrocarbon products in trace amounts. The mechanistic channels describing the formation of the major product succinimide have been explored. The detection of succinimide (major product) and maleimide (minor product) from the thermal decomposition of glutamic acid has been reported for the first time in this study. Toxicological implications of some reaction products (HCN, acetonitrile, and acyrolnitrile), which are believed to form during heat treatment of food, tobacco burning, and drug processing, have been discussed in relation to the thermal degradation of glutamic acid.
- Kibet, Joshua K.,Khachatryan, Lavrent,Dellinger, Barry
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p. 7696 - 7704
(2013/09/02)
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- Expedient one-step synthesis of nitrogen stilbene analogs by transition metal-free hydroamination of arylacetylenes with pyrroles
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A novel family of nitrogen stilbene analogs, 1-styrylpyrroles, has been synthesized in good to excellent yields by a straightforward facile transition metal-free addition of pyrroles to arylacetylenes in the KOH/DMSO system (90-120 °C, 5-13 h). Thermodynamically controlled E/Z-isomer ratio of 1-styrylpyrroles depends on structure of both pyrroles and acetylenes ranging from ca. 100% E-stereoselectivity (for the pair unsubstituted pyrrole - phenylacetylene) to 90, 96% Z-stereoselectivity (for the pairs: 2-phenylpyrrole - phenylacetylene and 2-(2-thienyl)pyrrole - phenylacetylene, respectively).
- Dvorko, Marina Yu.,Schmidt, Elena Yu.,Glotova, Tatyana E.,Shabalin, Dmitrii A.,Ushakov, Igor A.,Kobychev, Vladimir B.,Petrushenko, Konstantin B.,Mikhaleva, Al'Bina I.,Trofimov, Boris A.
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body text
p. 1963 - 1971
(2012/03/22)
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- Direct synthesis of chiral 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrazines via a catalytic asymmetric intramolecular aza-Friedel-Crafts reaction
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The direct asymmetric intramolecular aza-Friedel-Crafts reaction of N-aminoethylpyrroles with aldehydes catalyzed by a chiral phosphoric acid represents the first efficient method for the preparation of medicinally interesting chiral 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrazines with high yields and high enantioselectivities. This strategy has been shown to be quite general toward various aldehydes and pyrrole derivatives.
- He, Yuwei,Lin, Maohui,Li, Zhongmin,Liang, Xinting,Li, Guilong,Antilla, Jon C.
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supporting information; scheme or table
p. 4490 - 4493
(2011/10/09)
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- An efficient method for the synthesis of unsymmetrical 2,2′- bis(pyrrolyl)alkanes
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A new strategy for the preparation of unsymmetrical 2,2′- bis(pyrrolyl)alkanes has been developed. It involved the condensation of pyrrole derivatives onto N-benzylhydroxylamines in the presence of HCl. This two-step procedure provided access to a wide variety of 2,2′-dipyrromethanes (3a-m). It has also been extended to the synthesis of tripyrromethanes 4a-d and of N-confused dipyrromethanes 6a-d.
- Murat-Onana, Marie Laure,Berini, Christophe,Minassian, Frederic,Pelloux-Leon, Nadia,Denis, Jean-Noel
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body text
p. 2204 - 2211
(2010/07/04)
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- 2- (PIPERIDIN-1-YL) -4-HETEROCYCLYL-THIAZOLE-5-CARBOXYLIC ACID DERIVATIVES AGAINST BACTERIAL INFECTIONS
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Compounds of formula (I) and their pharmaceutically acceptable salts are described. Processes for their preparation, pharmaceutical compositions containing them, their use as medicaments and their use in the treatment of bacterial infections are also described. Ring A is selected from formula (a), (b) or (b'):
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Page/Page column 175-176
(2010/07/02)
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- One-pot assembly of 4-methylene-3-oxa-1-azabicyclo[3.1.0]hexanes from alkyl aryl(hetaryl) ketoximes, acetylene, and aliphatic ketones: a new three-component reaction
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A new three-component reaction between alkyl aryl(hetaryl)ketoximes, acetylene, and aliphatic ketones in the superbasic systems KOH/DMSO and LiOH/CsF/DMSO (70-90 °C, initial acetylene pressure 13-15 atm, 5-60 min) affords novel 4-methylene-3-oxa-1-azabicy
- Trofimov, Boris A.,Schmidt, Elena Yu.,Mikhaleva, Al'bina I.,Ushakov, Igor A.,Protsuk, Nadezhda I.,Senotrusova, Elena Yu.,Kazheva, Olga N.,Aleksandrov, Grigorii G.,Dyachenko, Oleg A.
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body text
p. 3314 - 3317
(2009/08/09)
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- PYRROLE ANTIFUNGAL AGENTS
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The invention provides compounds of formula (I), and pharmaceutically and agriculturally acceptable salts thereof; wherein: R1, R2, R3, R4, R5, R6, A1, L1 and n are as defined herein. These compounds and their pharmaceutically acceptable salts are useful in prevention or treatment of a fungal disease. Compounds of formula (I), and agriculturally acceptable salts thereof, may also be used as agricultural fungicides.
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Page/Page column 107
(2009/12/05)
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- In Situ vinylpyrrole synthesis. Diels-alder reactions with maleimides to give tetrahydroindoles
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(Chemical Equation Presented) A series of 108 tetrahydroindoles has been prepared by a one-pot synthesis from 2-alkylpyrroles, cyclic ketones, maleimides, and an acid catalyst. A 5-vinylpyrrole is formed by an acid-catalyzed condensation of a 2-alkyl-substituted pyrrole with a ketone, which is subsequently trapped in situ by a maleimide in a predominantly endo-addition Diels-Alder reaction. Isomerization of the double bond into the pyrrole ring gives a tetrahydroindole with predominant cis-fusion of the cycloalkane ring.
- Noland, Wayland E.,Lanzatella, Nicholas P.,Sizova, Elena P.,Venkatraman, Lakshmanan,Afanasyev, Oleg V.
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scheme or table
p. 503 - 534
(2009/09/05)
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- Self-assembly via intermolecular hydrogen-bonding between o-/m-/p-NH2 and BF2 groups on dipyrromethenes
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Boron difluoride dipyrromethenes bearing configurationally different amine groups on a meso-phenyl ring were prepared and crystallized. The ortho- and para-amino groups allow the phenyl group to inductively release greater electron density into the dipyrromethenes resulting in relatively strong intermolecular hydrogen-bonding with the terminal BF2 groups, whereas the meta-analog formed weaker hydrogen-bonds. The intensities of the 1H NMR peaks in concentrated solutions all increased with F-decoupling.
- Shin, Ji-Young,Patrick, Brian O.,Dolphin, David
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p. 5515 - 5518
(2008/12/22)
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- Boradiazaindacene dyes for technology of biological microchips
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A number of boradiazaindacene dyes containing a carboxyl group separated from a fluorophore by two methylene units were synthesized. The compounds have narrow spectral bands with absorption maxima at 480-530 nm and fluorescence maxima at 500-550 nm. Succinimide esters of these compounds and the corresponding fluorescent-labeled oligonucleotides were also prepared. Boradiazaindacene dyes can be used as fluorescent labels for oligonucleotides for analysis of melting curves of duplexes on microchips either by themselves or in combination with Texas Red. They can also be applied for labeling primers for polymerase chain reaction.
- Belobritskaya,Neunylova,Vasiliskov,Rumyantseva,Chudinov,Zasedatelev
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p. 617 - 619
(2008/03/27)
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- Photoinduced cytotoxicity and thioadduct formation by a prodigiosin analogue
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(Chemical Equation Presented) The prodigiosin alkaloid 1 and the synthetic analogue 2 show photoinduced cytotoxicity against HL-60 cancer cells. Photoirradiation of 1 and 2 causes photofading, photooxidation, and thioadduct formation. These results provide a model for the redox properties of prodigiosins that play a role in their biological activity and provide a new way to functionalize their pyrromethene entity with water-soluble thiol groups.
- Tomlinson, John T.,Park, Gyungse,Misenheimer, Jacob A.,Kucera, Gregory L.,Hesp, Kevin,Manderville, Richard A.
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p. 4951 - 4954
(2007/10/03)
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- Pyrrolotriazine inhibitors of kinases
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The present invention provides compounds of formula I and pharmaceutically acceptable salts thereof. The formula I compounds inhibit the tyrosine kinase activity of growth factor receptors such as VEGFR-2, FGFR-1, PDGFR, HER-1, HER-2, thereby making them useful as anti-cancer agents. The formula I compounds are also useful for the treatment of other diseases associated with signal transduction pathways operating through growth factor receptors.
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Page/Page column 26
(2008/06/13)
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- CHEMICAL COMPOUNDS
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Compounds of formula (I) and their pharmaceutica11y acceptable salts are described:Processes for their preparation,pharmaceutical compositions containing them, their use as medicaments and their use in the treatment of bacterial infections are also described
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Page/Page column 60
(2008/06/13)
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- ANTIBACTERIAL PIPERIDINE DERIVATIVES
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Compounds of formula (I) and their pharmaceutically acceptable salts are described: Formula (I). Processes for their preparation, pharmaceutical compositions containing them, their use as medicaments and their use in the treatment of bacterial infections are also described.
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Page/Page column 77-78
(2008/06/13)
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- TRICYCLIC DERIVATIVES OF AZETIDINE AND PYRROLE WITH ANTIBACTERIAL ACTIVITY
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Compounds of formula (I) and their pharmaceutically acceptable salts are described. Processes for their preparation, pharmaceutical compositions containing them, their use as medicaments and their use in the treatment of bacterial infections are also described.
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Page/Page column 55
(2008/06/13)
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- CHEMICAL COMPOUNDS
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Compounds of formula (I) and their pharmaceutically acceptable salts are described: Formula (I). Processes for their preparation, pharmaceutical compositions containing them, their use as medicaments and their use in the treatment of bacterial infections are also described.
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Page/Page column 68
(2010/11/23)
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- Cu(I)/Bis(azaferrocene)-catalyzed enantioselective synthesis of β-lactams via couplings of alkynes with nitrones
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As a consequence of the wide-ranging significance of β-lactams (e.g., use as drugs and as chiral building blocks), a great deal of effort has been dedicated to the development of methods for their stereoselective synthesis. Although considerable progress has been achieved, nearly all of the approaches that have been described are based on the use of chiral precursors; direct catalytic enantioselective routes to β-lactams are rare as well as limited in scope. In this communication, we establish that, using a new C2-symmetric planar-chiral bis(azaferrocene) ligand, we can generate β-lactams with very good enantiomeric excess and cis diastereoselection via catalytic enantioselective Kinugasa reactions (couplings of alkynes with nitrones). Appealing attributes of this process include the ready availability of the starting materials, the functional-group tolerance of the reaction, and the convergency of the approach. Copyright
- Lo, Michael M.-C.,Fu, Gregory C.
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p. 4572 - 4573
(2007/10/03)
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- Aromatic derivatives substituted by a ribose, their method of preparation and application as medicine
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A subject of the invention is the compounds of formula (I): R1=H, OH, alkyl, alkenyl or alkynyl optionally substituted or alkoxy, R2=H, Hal, R3=H, alkyl, Hal, Rg and Rh: H, alkyl, aryl heterocycle, R5=H or O-alkyl, R6=alkyl or CH2—O-alkyl, R7=H or alkyl. The compounds of formula (I) have antibiotic properties.
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Page column 7
(2010/02/04)
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- Synthesis and thermal stability of O-vinylketoximes
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The O-vinylketoximes 2 were synthesized from ketoximes 1 and acetylene in superbase systems in good to excellent yields. Their thermal stability was investigated.
- Trofimov, Boris A.,Al'bina, Mikhaleva I.,Vasil'tsov, Alexander M.,Schmidt, Elena Yu.,Tarasova, Ol'ga A.,Morozova, Ludmila V.,Sobenina, Lubov' N.,Preiss, Thomas,Henkelmann, Jochem
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p. 1125 - 1132
(2007/10/03)
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- Conjugated macrocycles related to the porphyrins. Part 16.1 synthesis of hexa- and heptaalkyl-substituted inverted or N-confused porphyrins by the "3 + 1" methodology
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Pyrrole-2,4-dicarboxaldehydes 13a-c were condensed with a tripyrrane dicarboxylic acid 12 in 1% TFA-CH2Cl2 to give, following oxidation with 0.1% FeCl3, a series of "etio-type" N-confused porphyrins 14a-c. Excellent yields were obtained when the diformylpyrrole possessed a 5-alkyl substituent, although the products were most easily isolated in the form of their hydrochloride salts. Addition of TFA to the free base inverted porphyrins led to initial protonation onto the external nitrogen atom to produce monocations 19 and further acidification afforded a dications 21. UV-vis spectroscopy showed strong Soret bands for 14, 19, and 21, features that are associated with fully aromatic porphyrinoid systems, and proton NMR spectroscopy confirmed the presence of powerful diamagnetic ring current where the meso-protons resonated near 10 ppm while the interior CH was strongly shielded to -6 ppm for the free base structures and -4 ppm for the dications 21. Taking into account the effect of the introduction of delocalized positive charges within the protonated species, the diatropic character of the macrocyclic system appeared to be slightly decreased upon protonation. Proton NMR spectroscopy demonstrated that a single tautomer was favored for the free base porphyrinoids 14 and furthermore NH exchange was slow on the NMR time scale even at room temperature. While this is not a factor for the dications, deuterium exchange was noted by NMR spectroscopy for the interior CH upon addition of TFA-d, indicating that C-protonated species are present in equilibrium with 21 and/or 19. Addition of a series of mineral acids (HF, HC1, HBr, HI, and HNO3) to solutions of 14 produced dications with significantly different UV-vis and NMR spectra, and these data indicate that strong ion pairing is occurring at the external NH. Reaction of 14 with nickel(II) acetate in DMF at 145°C afforded a relatively unstable nickel complex 25. Proton NMR spectra for 25 indicated that the macrocyclic ring current was considerably reduced, as would be expected for a cross-conjugated structure of this type. However, addition of TFA resulted in an unprecedented C-protonation that produced a new nickel(II)-containing aromatic species 29 that slowly demetalated to form the dication 21. The new results demonstrate that the alkyl-substituted inverted porphyrin series has many unique properties and the improved synthetic procedures will facilitate future investigations.
- Lash, Timothy D.,Richter, Daniel T.,Shiner, Craig M.
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p. 7973 - 7982
(2007/10/03)
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- Experimental and theoretical study of the isomerisation of N-methylpyrrole
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The isomerisation of N-methylpyrrole to 2-methylpyrrole has been investigated experimentally by means of a single pulse shock tube over the temperature range 1000 to 1350 K and theoretically by ab initio calculations.Between 1000 and 1100 K the isomerization is found to occur via an intramolecular methyl shift.The experimental rate constant for this rearrangement was found to be kiso = 1E12.8(+/-0.4) exp-1/RT> s-1.Ab initio calculations gave Arrhenius parameters for the methyl shift in good agreement with the experimental values.Methyl shifting produces the intermediate 2-methyl-2H-pyrrole which undergoes a hydrogen shift of low activation energy to form the product of isomerisation, 2-methylpyrrole.Above about 1240 K there is a competing free-radical process which produces methane, pyrrole and traces of higher molecular weight products.
- Doughty, Alan,Mackie, John C.,Bacskay, George B.
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p. 267 - 273
(2007/10/02)
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- Synthesis of Alkylpyrroles via O/N Transformation of 2-Methylfuran over HZSM-5 Zeolite
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The heterogeneous catalytic synthesis of alkylpyrroles from 2-methylfuran and ammonia, methyl-, ethyl- and n-propyl-amine by O/N transformation over HZSM-5 zeolite is reported.
- Martin, Andreas,Luecke, Bernhard
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p. 1745 - 1746
(2007/10/02)
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- Chemical synthesis of a 'GSA-pyrrole' and its reaction with Ehrlich's reagent
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A rational chemical synthesis of 4-acetyl-2-(2-carboxyethyl)-5-methylpyrrole (5), the product formed when glutamate-1-semialdehyde (GSA, 2) is reacted with acetylacetone in the first step of the quantitative analysis for GSA in biological media. Rates of reaction of the GSA-pyrrole (5) with Ehrlich's reagent (the second step in GSA quantitation) are compared with the rates of the reactions of well-characterized 'ALA-pyrroles' (3) and (4). Pyrrole (5) reacts more slowly with Ehrlich's reagent, and extinction coefficients for the corresponding Ehrlich's adducts were determined to be 46,000 for (3) and 865 for (5). These observations resolve the discrepancies observed in earlier quantitations of GSA and allow more accurate determinations of it in biological materials.
- Liddell,Forsyth,Senge,Smith
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p. 1343 - 1350
(2007/10/02)
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- REARRANGEMENT OF 1-PIPERIDINOCYCLOPROPYL KETIMINES. A SYNTHESIS OF 2-SUBSTITUTED PYRROLES
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On heating 1-(N-piperidino)cyclopropyl ketimines with HBF4, rearrangement to 2-substituted pyrroles takes place.
- Wasserman, Harry H.,Dion, Robert P.,Fukuyama, James M.
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p. 629 - 631
(2007/10/02)
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- Thermolysis of Polyazapentadienes. Part 9. Gas Phase Thermolysis of Some Dienamines, Enaminones, and Enaminothiones
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Thermolysis of the title compounds gives low yields of pyrroles by hydrogen-transfer-cyclisation-aromatisation sequence.The results are best explained by a dipolar mechanism for the hydrogen-transfer step: competitive aromatisation routes account for the range of substituted pyrroles which were obtained.
- Hickson, Clare L.,McNab, Hamish
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p. 339 - 342
(2007/10/02)
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- Chemically reactive dipyrrometheneboron difluoride dyes
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Novel fluorescent dyes based on the dipyrrometheneboron difluoride structure are provided. The new reagents contain functional groups capable of forming a stable fluorescent product with functional groups typically found in biomolecules or polymers including amines, phenols, thiols, acids, aldehydes and ketones. Reactive groups in the dipyrrometheneboron difluoride dyes include activated esters, isocyanates, amines, hydrazines, sulfonyl halides, acids, aldehydes, alcohols and haloacetamides. The products are detected by their absorbance or fluorescence properties. The spectral properties of the fluorescent dyes are sufficiently similar in wavelengths and intensity to fluorescein as to permit use of the same euqipment. The dyes, however, have narrower spectral bandwidths than fluorescein, do not show appreciable sensitivity to pH, have higher solubility in non-polar solvents and have improved photostability.
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- PYRROLES FROM KETOXIMES AND ACETYLENE. 29. SYNTHESIS OF ALKYLPYRROLES FROM DIALKYLKETOXIMES AND DICHLOROETHANE BY REACTION WITH KOH-DMSO
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Treatment of dialkylketoximes with dichloroethane and KOH-DMSO results in the formation of alkylpyrroles in 31-61percent yields.In addition, the corresponding 1-vinylpyrroles are formed simultaneously in yields up to 18percent.The corresponding 1,2-bis(alkylideneiminoxy)ethanes are obtained as side products in the reaction; they result from nucleophilic displacement of chlorine atoms by oximate anions.
- Trofimov, B. A.,Mikhaleva, A. I.,Vasil'ev, A. N.,Korostova, S. E.,Shevchenko, S. G.
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- Synthesis of Alkylpyrroles by the Sodium Borohydride Reduction of Acylpyrroles
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N-Unsubstituted alkylpyrroles are obtained by the reduction of the corresponding acylpyrroles with sodium borohydride in boiling 2-propanol.This reaction was demonstrated to proceed via the pyrrolylalkylcarbinol and was extended to the synthesis of a branched chain alkylpyrrole 25 from the tertiary alcohol 24.
- Greenhouse, Robert,Ramirez, Coral,Muchowski, Joseph M.
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p. 2961 - 2965
(2007/10/02)
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- Process for the preparation of a 2-alkylpyrrole
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A process is described for the catalytic gas phase reduction of 4-oxoalkanenitriles to form 2-alkylpyrroles in high yields and conversions.
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- Gas-Phase Heteroaromatic Substitution. 2. Electrophilic Methylation of Pyrrole and N-Methylpyrrole by CH3XCH3+ (X = F or Cl) Ions
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The gas-phase methylation of pyrrole (1) and N-methylpyrrole (2) by CH3XCH3+ (X = F or Cl) ions, from the γ radiolysis of CH3X, has been investigated at pressure ranging from 50 to 760 torr, in the presebce of a thermal radical scavenger (O2) and variable concentrations of an added base (NMe3).Both the reactivity of the selected pyrroles relative to benzene, used as the refernce substrate in competition experiments, and the isomeric distribution of their methylated derivatives depende markedly on the total pressure of the system and the concentration of NMe3.The apparent kP/kB ratios increase from 0.2 (1)-0.3 (2), in neat CH3F at 50 torr, to over 0.4 (1)-1.0 (2), at 760 torr containing 10 torr of NMe3.Concurently, the isomeric distribution of the methylated products changes from β:α:N = 80percent:13percent:7percent (from 1) and β:α = 65percent:35percent (from 2) to β:α:N = 50percent:15percent:35percent and β:α = 70percent:30percent.These results are consistent with a methylation mechanism involving kinetically predominant CH3FCH3+ attack on the β-carbons of the pyrrolic substrate and subsequent isomerization of the resulting excited intermediates to the thermodynamically most stable 3-methylpyrrole protonated on the 2-position.The substrate and positional selectivity of the gas-phase methylation and the mechanism of isomerization that appears of intramolecular nature are discussed in the light of the recent theoretical predictions on heteroaromatic reactivity and compared with the available data of related methylation reactions, occuring both in the gaseous and condensed phase.
- Angelini, Giancarlo,Sparapani, Cinzia,Speranza, Maurizio
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p. 7084 - 7091
(2007/10/02)
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- Synthesis and Intramolecular Cycloaddition Reactions of Some 3-Substituted 6-Azidohexa-2,4-dienoate Esters
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Several 3-substituted (methyl, n-butyl, phenyl) 6-azidohexa-2,4-dienoate esters were synthesized by conjugate addition of -1-propenyl>copper to the appropriate acetylenic ester, followed by conversion to the azide by depyranylation , mesylation, and azide substitution.In the methyl and butyl cases, the addition was nonstereoselective under the conditions used, while the phenyl case gave nearly completely the product of anti addition.The azides all undergo intramolecular cycloaddition to form 3a,6-dihydro-3H-pyrrolotriazolesat rates which depend upon the stereochemistry and substitution of the 6-azidohexa-2,4-dienoate.All of these adducts are unstable with respect to decomposition to a 2-substituted pyrrole, again at rates which are both substituent and solvent dependent.Under certain circumstances, the 3a,6-dihydro-3H-pyrrolotriazoles are converted to the open chain valence tautomers which are α-diazo-2,5-dihydropyrrole-2-acetate esters.Possible factors contributing to the observed substituent and stereochemical effects are considered.
- Sundberg, Richard J.,Pearce, Brad C.
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p. 725 - 730
(2007/10/02)
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- First Example of Predominant β-Orientation in Electrophilic Substitution of Pyrrole
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The isomeric distribution of the neutral products from the gas-phase electrophilic attack of 3He3H+, CH3FCH3+, and t-C4H9+ ions on pyrrole provides the first experimental evidence for predominant β-orientation in electrophilic substitution of pyrrole .
- Speranza, Maurizio
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p. 1177 - 1178
(2007/10/02)
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- Pharmaceutical compositions and methods of inhibiting gastric acid secretion
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Pharmaceutical compositions and methods of inhibiting gastric acid secretion by administering N-alkenyl and N-alkynyl thioamides.
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