- A new insight into the push-pull effect of substituents via the stilbene-like model compounds
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In this paper, authors report on 1-pyridyl-2-arylethenes, 1-furyl-2-arylethylenes, 1,2-diphenylpropylenes and substituted cinnamyl anilines as stilbene-like model compounds to investigate the factors dominating the push-pull effect of substituents via usi
- Cao, Chaotun,Cao, Chenzhong,Zeng, Zhao
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- Determination and application of the excited-state substituent constants of pyridyl and substituted phenyl groups
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Thirty six 1-pyridyl-2-arylethenes XCH=CHArY (abbreviated XAEY) were synthesized, in which, X is 2-pyridyl, 3-pyridyl and 4-pyridyl and Y is OMe, Me, H, Br, Cl, F, CF3, and CN. Their ultraviolet absorption spectra were measured in anhydrous ethanol, and their wavelengths of absorption maximum λmax were recorded. Also, the 234 λmax values of 1-substituted phenyl-2-arylethylene compounds (XAEY, where X is substituted phenyl) were collected. The excited-state substituent constants (Formula presented.) of three pyridyl groups and 23 substituted phenyl groups (total of 26) were obtained by means of curve-fitting method. Taking the λmax values of 358 samples of bi-arylethene derivatives as a data set and 126 samples of bi-aryl Schiff bases (including nine compounds synthesized by this work) as another data set, quantitative correlation analyses were performed by employing the obtained (Formula presented.) as a parameter, and good results were obtained for the two data sets. The reliability of the obtained (Formula presented.) values was verified. The results of this paper can provide excited-state substituent constants for the study and application of optical properties of conjugated organic compounds containing aryl groups.
- Cao, Chao-Tun,Yan, Lu,Cao, Chenzhong
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- Effect of N-substituent in 4-styrylpyridinium dyes on their binding to DNA
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4-Styrylpyridinium dyes containing N-methyl and N-(3-pyridiniopropyl) substituents have been prepared and characterized by optical and CD spectroscopy. These compounds demonstrate affinity to calf thymus DNA, with dye–DNA binding mode being different for
- Chernikova, Polina A.,Fedorov, Yury V.,Fedorova, Olga A.,Shepel, Nikolai E.,Ustimova, Maria A.
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p. 217 - 219
(2020/05/25)
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- Short Wavelength Inner Filter Technique (SWIFT) in Designing Reactive Fluorescent Molecular Probes
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Here, we present a conceptually novel and experimentally straightforward technique for selective analyte detection that uses a combination of commercial fluorophores and simple chemicals. The technique utilizes the well-known inner filter effect (IFE); however, the fluorophore's excitation is performed at wavelengths significantly shorter than its absorption maximum. In the presence of the analyte, the "filter" appears or disappears at the excitation wavelength resulting in the fluorescence turning OFF or ON, respectively. Unlike common probes, our technique allows real-time monitoring of a fluorophore's stability as well as its recycling. We further demonstrate the applicability of this technique in continuing analyte detection as well as vapor analysis.
- Baheti, Abhishek,Vigalok, Arkadi
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supporting information
p. 12224 - 12228
(2019/08/21)
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- 1,4-Diphenalkylpiperidines: A new scaffold for the design of potent inhibitors of the vesicular monoamine transporter-2
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A series of 1,4-diphenalkylpiperidine analogs were synthesized and evaluated for their affinity and inhibitory potency at the [3H]dihydrotetrabenazine (DTBZ) binding site and [3H]dopamine (DA) uptake site on the vesicular monoamine transporter-2 (VMAT2). Results revealed that translocation of the phenethyl side chains of lobelane from C2 and C6 to C1 and C4 around the central piperidine ring slightly reduces affinity and inhibitory potency at VMAT2 with respect to lobelane. However, methoxy and fluoro-substitution of either phenyl ring of these 1,4-diphenethyl analogs afforded VMAT2 inhibition comparable or higher (5-fold) affinity at the DTBZ binding and DA uptake sites relative to lobelane, whereas replacement of the 4-phenethyl moiety in these analogs with a 4-phenmethyl moiety markedly reduced affinity for the DTBZ binding and DA uptake sites by 3- and 5-fold, respectively. Among the twenty five 1,4-diphenethylpiperidine analogs evaluated, compounds containing a 4-(2-methoxyphenethyl) moiety exhibited the most potent inhibition of DTBZ binding and vesicular DA uptake. From this subgroup, analogs 8h, 8j and 8m exhibited Ki values of 9.3 nM, 13 nM and 13 nM, respectively, for inhibition of [3H]DA uptake by VMAT2, and represent some of the most potent inhibitors of VMAT2 function reported thus far.
- Nickell, Justin R.,Culver, John P.,Janganati, Venumadhav,Zheng, Guangrong,Dwoskin, Linda P.,Crooks, Peter A.
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supporting information
p. 2997 - 3000
(2016/06/13)
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- Inhibitory effect of cytotoxic nitrogen-containing heterocyclic stilbene analogues on VEGF protein secretion and VEGF, hTERT and c-Myc gene expression
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A group of 21 nitrogen-containing heterocyclic stilbene derivatives, prepared by means of Heck coupling reactions, has been investigated for their cytotoxicity as well as their ability to inhibit the production of the vascular endothelial growth factor (VEGF) and the activation of telomerase. The ability of these compounds to inhibit proliferation of two tumoral cell lines (HT-29 and MCF-7) and one non-tumoral cell line (HEK-293) was first determined. Subsequently, we determined the capacity of the compounds to inhibit the secretion of VEGF in the aforementioned cell lines and downregulate the expression of the VEGF, hTERT and c-Myc genes, of which the latter two are involved in controlling the activation of telomerase.
- Martí-Centelles, Rosa,Murga, Juan,Falomir, Eva,Carda, Miguel,Alberto Marco
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supporting information
p. 1809 - 1815
(2015/10/20)
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- (E)-Specific direct Julia-olefination of aryl alcohols without extra reducing agents promoted by bases
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An unprecedented base-promoted direct olefination of aryl alcohols with sulfones via a Julia-type reaction has been described. No extra reductants are needed for Julia reaction since alcohols work as double sources of aldehydes and the hydride. Generally high yields were given for both terminal and highly (E)-selective internal olefins.
- Yao, Chuan-Zhi,Li, Qiang-Qiang,Wang, Mei-Mei,Ning, Xiao-Shan,Kang, Yan-Biao
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supporting information
p. 7729 - 7732
(2015/05/12)
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- Heck cross-coupling of vinyl heteroaromatic compounds with aryl and heteroaryl halides using Pd(II) complex under phosphine-free conditions
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The palladium-catalyzed cross-coupling reaction of vinyl heteroaromatic compounds with aryl bromides and heteroaryl bromides is described using air and moisture stable N,N′,N″,O-tetrafunctional Pd catalyst under phosphine-free conditions. As a result a variety of trans-1,2-disubstituted vinyl heterocycles were obtained in high to good yields.
- Annapurna, Manne,Vishnuvardhan Reddy,Singh, Surya Prakash,Kantam, Mannepalli Lakshmi
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p. 10940 - 10945
(2014/01/06)
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- Mizoroki-Heck reactions catalyzed by palladium dichloro-bis(aminophosphine) complexes under mild reaction conditions. the importance of ligand composition on the catalytic activity
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Dichloro-bis(aminophosphine) complexes of palladium with the general formula [(P{(NC5H10)3-n(C6H 11)n})2Pd(Cl)2] (where n = 0-2) are easily accessible, cheap and air stable, highly active and universally applicable C-C cross-coupling catalysts, which exhibit an excellent functional group tolerance. The ligand composition of amine-substituted phosphines (controlled by the number of P-N bonds) was found to effectively determine their catalytic activity in the Heck reaction, for which nanoparticles were demonstrated to be their catalytically active form. While dichloro{bis[1, 1′,1′′-(phosphinetriyl)tripiperidine]}palladium (1), the least stable complex (towards protons) within the series of [(P{(NC5H 10)3-n(C6H11)n}) 2Pd(Cl)2] (where n = 0-3), is a highly active Heck catalyst at 100 °C and, hence, a rare example of an effective and versatile Heck catalyst that efficiently operates under mild reaction conditions (100 °C or below), a significant successive drop in activity was noticed for dichloro-bis(1,1′-(cyclohexylphosphinediyl)dipiperidine)palladium (2, with n = 1), dichloro-bis(1-(dicyclohexylphosphinyl)piperidine)palladium (3, with n = 2) and dichloro-bis(tricyclohexylphosphine)palladium (4, with n = 3), of which the latter is essentially inactive (at least under the reaction conditions applied). This trend was explained by the successively increasing complex stability and its ensuing retarding effect on the (water-induced) generation of palladium nanoparticles thereof. This interpretation was experimentally confirmed (initial reductions of 1-4 into palladium(0) complexes of the type [Pd(P{(NC5H10)3-n(C6H 11)n})2] (where n = 0-3) were excluded to be the reason for the activity difference observed as well as molecular (Pd 0/PdII) mechanisms were excluded to be operative) and thus demonstrates that the catalytic activity of dichloro-bis(aminophosphine) complexes of palladium can-in reactions where nanoparticles are involved-effectively be controlled by the number of P-N bonds in the ligand system.
- Oberholzer, Miriam,Frech, Christian M.
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supporting information
p. 1678 - 1686
(2013/10/01)
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- Ligand-free palladium-catalysed oxidative Heck reaction of 4-vinylpyridine with arylboronic acids: Selective synthesis of (E)-4-styrylpyridines
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A ligand-free palladium-catalysed oxidative Heck reaction of various arylboronic acids with 4-vinylpyridine has been developed, achieving (E)-4-styrylpyridines with high selectively in moderate to good yields. A plausible mechanism for the formation of (E)-4-styrylpyridines has been proposed.
- Shi, Chuanli,Ding, Jinchang,Jiang, Jun,Chen, Jiuxi,Wu, Huayue,Liu, Miaochang
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supporting information; experimental part
p. 322 - 325
(2012/09/21)
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- Rationally designed pincer-type heck catalysts bearing aminophosphine substituents: PdIV intermediates and palladium nanoparticles
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The aminophosphine-based pincer complexes [C6H 3-2,6-{XP(piperidinyl)2}2Pd(Cl)] (X = NH 1; X = O 2) are readily prepared from cheap starting materials by sequential addition of 1,1′,1″-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to solutions of [Pd(cod)(Cl)2] (cod = cyclooctadiene) in toluene under N2 in "one pot". Compounds 1 and 2 proved to be excellent Heck catalysts and allow the quantitative coupling of several electronically deactivated and sterically hindered aryl bromides with various olefins as coupling partners at 140°C within very short reaction times and low catalyst loadings. Increased reaction temperatures also enable the efficient coupling of olefins with electronically deactivated and sterically hindered aryl chlorides in the presence of only 0.01 mol% of catalyst. The mechanistic studies performed rule out that homogeneous Pd0 complexes are the catalytically active forms of 1 and 2. On the other hand, the involvement of palladium nanoparticles in the catalytic cycle received strong experimental support. Even though pincer-type PdIV intermediates derived from 1 (and 2) are not involved in the catalytic cycle of the Heck reaction, their general existence as reactive intermediates (for example, in other reactions) cannot be excluded. On the contrary, they were shown to be thermally accessible. Compounds 1 and 2 show a smooth halide exchange with bromobenzene to yield their bromo derivatives in DMF at 100°C. Experimental observations revealed that the halide exchange most probably proceeded via pincer-type PdIV intermediates. DFT calculations support this hypothesis and indicated that aminophosphine-based pincer-type PdIV intermediates are generally to be considered as reactive intermediates in reactions with aryl halides performed at elevated temperatures.
- Bolliger, Jeanne L.,Blacque, Olivier,Frech, Christian M.
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experimental part
p. 7969 - 7977
(2009/09/08)
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- Entangled palladium nanoparticles in resin plugs
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Palladium nanoparticles were entrapped within resin plugs and used in a range of ligand-free cross-coupling reactions; the convenient modular format of the resin plug enhanced resin handling and allowed the catalysts to be easily recovered and multiply reused. The Royal Society of Chemistry.
- Najman, Romain,Cho, Jin Ku,Coffey, Andrew F.,Davies, John W.,Bradley, Mark
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p. 5031 - 5033
(2008/09/17)
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- Synthesis and anti-inflammatory activity of resveratrol analogs
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Seventeen novel resveratrol derivatives were synthesized. Their anti-inflammatory activities were tested on xylene-induced mouse ear edema. The pharmacological results showed that some compounds have potent anti-inflammatory activities.
- Chen, Guoliang,Shan, Wei,Wu, Yingliang,Ren, Lixiang,Dong, Jinhua,Ji, Zhizhong
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p. 1587 - 1590
(2007/10/03)
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- Synthesis, structural characterization and solvatochromic studies of a series of Schiff base-containing triosmium alkylidyne carbonyl clusters
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A series of new Schiff base-containing triosmium alkylidyne carbonyl clusters [Os3(μ-H)2(CO)9(μ3-CNC 5H4CH=NC6H4R)] (R = H, NMe2, SMe, CMe3, NHs
- Wong, Wai-Yeung,Wong, Wing-Tak
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- Mesomorphic metal complexes derived from 4-alkyloxystilbazoles
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The weakly mesomorphic trans-4-alkyloxy-4′-stilbazoles (n-OPhVPy) are readily synthesised from alkyloxyiodobenzenes and 4-vinylpyridine in a palladium-catalysed Heck reaction. While the highly symmetric palladium and platinum complexes trans-[MCl2(n-OPhVPy)2] show mesophases only at very high temperatures, the lower symmetry platinum complexes trans-[PtCl2(η2-olefin) (n-OPhVPy)] melt below 100°C. Similarly, the complexes [MCl(CO)2(n-OPhVPy)] (M = Rh, Ir) are low melting. The silver complexes [Ag(n-OPh VPy)2][X] (X = C12H25OSO3, C8H17OSO3, CF3SO3) can be obtained by direct reaction of the stilbazole with AgX. These ionic materials show a rich thermotropic polymorphism, including nematic and cubic mesophases. Some fluorinated stilbazoles have also been synthesised and complexed to silver; the mesomorphism of these complexes is also reported.
- Bruce,Davis,Dunmur,Hudson,Maitlis,Styring
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- CHARACTERISTIC FEATURES OF THE CONDENSATION OF PICOLINE BORON TRIFLUORIDE COMPLEXES WITH AROMATIC ALDEHYDES
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The formation of complexes 2- and 4-picolines with BF3 results in a significant activation of their methyl groups.This makes it possible to carry out condensations with aromatic aldehydes under mild conditions.The reaction of 2-picoline with 4-(dimethylamino)benzaldehyde in acetic anhydride solution results in the splitting of the pyridine ring with formation of an unstable product.
- Vasil'ev, A. N.,Mushkalo, L. K.
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p. 1718 - 1720
(2007/10/02)
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- Kinetics of Reaction of Phenacyl Bromide with 3- and 4-Substituted Pyridines and 4-Substituted 4-Styrylpyridines
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The rates of reaction of phenacyl bromide with 3- and 4-substituted pyridines and 4'-substituted 4-styrylpyridines have been measured in aq. acetone (90percent, v/v) at 30 deg C, 35 deg C and 40 deg C and the activation parameters have been evaluated.Satisfactory Hammett correlations are obtained for both pyridine and styrylpyridine series.The effectiveness of transmission of substituent effect in styrylpyridine system relative to pyridine system in this reaction is calculated to be 0.104.From the Bronsted relationship the coefficient (βN) is found to be 0.48, indicating that the extent of bond formation in the transition state is moderate.
- Shunmugasundaram, A.,Balakumar, S.
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p. 775 - 777
(2007/10/02)
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- 1,2,3,4,6,7,8,8A-Octahydro-6-aryl-isoquinolines and derivatives thereof
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1,2,3,4,6,7,8,8a-Octahydro-6-phenyl or substituted phenyl-isoquinolines and derivatives thereof and their methods of preparation are disclosed. These compounds are useful as anti-inflammatory agents.
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