- Gas-phase heteroaromatic substitution. 8. Electrophilic attack of ethyl cation on pyrrole, N-methylpyrrole, furan, and thiophene
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Ethyl cation, obtained in the dilute gas state, together with CH5+, from the γ-radiolysis of methane, has been allowed to react with pyrrole, N-methylpyrrole, furan, and thiophene, in the pressure range 50-760 Torr and in the presence of variable concentrations of a gaseous base (NMe3). The mechanism of the substitution and of the subsequent isomerization of the relevant ionic intermediates is discussed, and the intrinsic positional selectivity of the C2H5+ ions is evaluated. Gas-phase C2H5+ ion attack on pyrroles is characterized by a significant positional selectivity toward those substrate positions with the highest net negative charge (N:α:β = 13%:10%:77% for pyrrole; α:β = 19%:81% for N-methylpyrrole). Interaction of C2H5+ with the furan center having the maximum value of the negative charge, i.e. the O atom, favors occurrence of α-substitution (α:β = 57%:43%). Thiophene displays no significant positional discrimination (α:β = 54%:46%). Gas-phase attack of C2H5+ on simple five-membered heteroaromatics is mainly governed by electrostatic interactions established within the encounter pair. This characterizes gaseous C2H5+ as a very ''hard'' electrophile, rather than a borderline acid, as expected on the grounds of the alkyl cation ''hardness'' scale. This deviation is explained in terms of the bridged geometry for C2H5+ and its effect on the LUMO energy level of the ion.
- Laguzzi,Bucci,Grandinetti,Speranza
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Read Online
- Pyrrole Hemithioindigo Antimitotics with Near-Quantitative Bidirectional Photoswitching that Photocontrol Cellular Microtubule Dynamics with Single-Cell Precision**
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We report the first cellular application of the emerging near-quantitative photoswitch pyrrole hemithioindigo, by rationally designing photopharmaceutical PHTub inhibitors of the cytoskeletal protein tubulin. PHTubs allow simultaneous visible-light imaging and photoswitching in live cells, delivering cell-precise photomodulation of microtubule dynamics, and photocontrol over cell cycle progression and cell death. This is the first acute use of a hemithioindigo photopharmaceutical for high-spatiotemporal-resolution biological control in live cells. It additionally demonstrates the utility of near-quantitative photoswitches, by enabling a dark-active design to overcome residual background activity during cellular photopatterning. This work opens up new horizons for high-precision microtubule research using PHTubs and shows the cellular applicability of pyrrole hemithioindigo as a valuable scaffold for photocontrol of a range of other biological targets.
- Akhmanova, Anna,Heise, Constanze,Meiring, Joyce C. M.,Pettersson, Linda N.,Sailer, Alexander,Thorn-Seshold, Julia,Thorn-Seshold, Oliver
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supporting information
p. 23695 - 23704
(2021/10/05)
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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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- Entropic Mixing Allows Monomeric-Like Absorption in Neat BODIPY Films
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Intermolecular interactions play a crucial role in materials chemistry because they govern thin film morphology. The photophysical properties of films of organic dyes are highly sensitive to the local environment, and a considerable effort has therefore been dedicated to engineering the morphology of organic thin films. Solubilizing side chains can successfully spatially separate chromophores, reducing detrimental intermolecular interactions. However, this strategy is also significantly decreasing achievable dye concentration. Here, five BODIPY derivatives containing small alkyl chains in the α-position were synthesized and photophysically characterized. By blending two or more derivatives, the increase in entropy reduces aggregation and therefore produces films with extreme dye concentration and, at the same time almost solution like absorption properties. Such a film was placed inside an optical cavity and the achieved system was demonstrated to reach the strong exciton-photon coupling regime by virtue of the achieved dye concentration and sharp absorption features of the film.
- Sch?fer, Clara,Mony, Jürgen,Olsson, Thomas,B?rjesson, Karl
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supporting information
p. 14295 - 14299
(2020/10/06)
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- Scalable Wolff-Kishner Reductions in Extreme Process Windows Using a Silicon Carbide Flow Reactor
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A safe and scalable continuous flow strategy for Wolff-Kishner reductions that employs methanol as the solvent has been developed. The use of low-cost hydrazine as the reducing agent in combination with a caustic base provides an atom-efficient, environmentally friendly method for the deoxygenation of aldehydes and ketones to alkanes. Because of the required harsh and corrosive reaction conditions (200 °C, 50 bar), reactor materials such as stainless steel, glass, or any type of polymer have compatibility problems, rendering this process problematic on a production scale. The use of corrosion-resistant silicon carbide (SiC) as the reactor material opens up the possibility of performing Wolff-Kishner reductions on scale with a considerably improved safety profile. Methanol as the solvent significantly simplifies the workup procedure compared with the generally employed high-boiling solvents such as diethylene glycol. The continuous flow protocol was applied to a number of substrates and provided the desired products in good to high yields with space-time yields of up to 152 g L-1 h-1. In addition, a pharmaceutically valuable active pharmaceutical ingredient precursor was synthesized by employing this higherature/pressure Wolff-Kishner protocol.
- Znidar, Desiree,O'Kearney-Mcmullan, Anne,Munday, Rachel,Wiles, Charlotte,Poechlauer, Peter,Schmoelzer, Christoph,Dallinger, Doris,Kappe, C. Oliver
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p. 2445 - 2455
(2019/11/03)
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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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- TAMBJAMINES AND B-RING FUNCTIONALIZED PRODIGININES
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Embodiments of tambjamines and B-ring functionalized prodiginines are disclosed. Methods of synthesizing and using the disclosed compounds are also disclosed. Some embodiments of the disclosed compounds have antimalarial activity. Certain embodiments of t
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Page/Page column 20; 21; 33
(2016/11/17)
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- Synthesis and Structure-Activity Relationships of Tambjamines and B-Ring Functionalized Prodiginines as Potent Antimalarials
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Synthesis and antimalarial activity of 94 novel bipyrrole tambjamines (TAs) and a library of B-ring functionalized tripyrrole prodiginines (PGs) against a panel of Plasmodium falciparum strains are described. The activity and structure-activity relationsh
- Kancharla, Papireddy,Kelly, Jane Xu,Reynolds, Kevin A.
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p. 7286 - 7309
(2015/10/05)
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- Modular access to complex prodiginines: Total synthesis of (+)-roseophilin via its 2-azafulvene prototropisomer
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Ansa-bridged prodiginines are bioactive pigments produced by bacteria. Certain of these structures are reported to be antagonists of protein-protein interactions involved in apoptosis. We describe a new entry to alkaloids of this type, demonstrated with a concise asymmetric synthesis of (+)-roseophilin (3). Our route constructs the pyrrolophane motif via phosphoryl transfer-terminated macroaldolization and passes through a previously unexplored prototropic form of the natural product.
- Frederich, James H.,Harran, Patrick G.
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supporting information
p. 3788 - 3791
(2013/04/10)
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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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- Deprotection of N-sulfonyl nitrogen-heteroaromatics with tetrabutylammonium fluoride
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The deprotection of N-methylsulfonyl, N-(p-toluenesufonyl), and N-phenylsulfonyl nitrogen-heteroaromatic compounds proceeds easily in excellent yields by refluxing with tetrabutylammonium fluoride (TBAF) in THF.
- Yasuhara, Akito,Sakamoto, Takao
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p. 595 - 596
(2007/10/03)
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- Influence of the reaction temperature on the regioselectivity in the rhodium-catalyzed hydroformylation of vinylpyrroles
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The influence of the temperature on the regioselectivity in the hydroformylation of the vinylpyrrole isomers and of the corresponding N-tosylated substrates has been investigated in the range 20-100°C, in the presence of Rh4(CO)12. At all the temperatures the branched aldehyde was prevailing with respect to the linear isomer for all the substrates ( α-regioselectivity). With increasing temperature, an increase of the linear aldehyde was observed to a different extent in dependence on the substrate nature. 2H NMR investigation of the crude reaction mixture recovered from deuterioformylation of 3-vinylpyrrole at partial substrate conversion points out that the observed depression of the α-regioselectivity with increasing temperature must be connected to a β-hydride elimination process occurring for the branched alkyl-rhodium intermediates but not for the linear ones.
- Caiazzo, Aldo,Settambolo, Roberta,Uccello-Barretta, Gloria,Lazzaroni, Raffaello
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p. 279 - 284
(2007/10/03)
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- SYNTHESIS OF PYRROLES FROM ALKYL trans-2-METHYLOXYCYCLOPROPYL KETONES
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2-Alkylpyrroles were obtained by the reaction of alkyl trans-2-methoxycyclopropyl ketones with ammonium hydroxide.N-Substituted 2-alkylpyrroles were synthesized by the reaction of the indicated ketones with methylamine or aniline in acetic acid or methano
- Romashin, Yu. N.,Nadim, Al Mohana,Kulinkovich, O. G.
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p. 1110 - 1111
(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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