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1.
《Electroanalysis》2004,16(7):539-546
Spectroelectrochemical and HPLC characterization of the electrochemical oxidation in aqueous medium of a series of six N‐1 and C‐4 substituted 1,4‐dihydropyridines is presented. Based on the analysis of spectra obtained by in situ spectroscopic measurements it was possible to detect the generation of final oxidation products, which resulted in differences depending of the nature of the substitution on the nitrogen in the dihydropyridine ring. Controlled potential electrolysis (CPE) in aqueous medium was followed by the HPLC technique using EC and PDA detectors. This latter resulted adequately to follow the parent 1,4‐DHP derivatives and their respective oxidation products. Electrochemical oxidation of parent N‐H substituted 1,4‐dihydropyridines generated the corresponding neutral pyridine derivative as final oxidation product. However, the N‐ethyl substituted 1,4‐dihydropyridine derivatives gave rise to the pyridinium salt derivatives. 相似文献
2.
The one‐pot four‐component reaction of benzohydrazide, acetylenedicarboxylate, aromatic aldehydes and malononitrile in ethanol with triethylamine as base catalyst afforded functionalized 1‐benzamido‐1,4‐dihydropyridines in satisfactory yields. Under similar conditions, picolinohydrazide or nicotinohydrazide can also be successfully utilized in the reactions to give corresponding functionalized 1,4‐dihydropyridines. 1H NMR data indicated that an equilibrium of cis/trans‐conformations exist in 1‐benzamido‐1,4‐dihydropyridines. 相似文献
3.
T.J. Van Bergen Titia Mulder R.A. Van Der Veen Richard M. Kellogg 《Tetrahedron》1978,34(15):2377-2383
Hydride exchange occurs between 3,5 - di(alkoxycarbonyl) - 1,4 - dihydropyridines and their corresponding pyridinium salts. For the case of 1,2,6 - trimethyl - 3,5 - di(ethoxycarbonyl) - 1,4 - dihydropyridine in the presence of the structurally corresponding pyridinium perchlorate, hydride is transferred to the 4-position of the pyridinium salt in a reversible “blind” reaction as revealed by deuterium labeling experiments and to the 2,6-positions irreversibly to afford 1,2,6 - trimethyl - 3,5 - di(ethoxycarbonyl) - 1,2 - dihydropyridine as final product. Removal of the methyl groups at the 2,6-positions, i.e. 1 - methyl - 3,5 - di(methoxycarbonyl) - 1,4 -dihydropyridine and its structurally corresponding pyridium perchlorate, causes hydride transfer to become completely reversible. Substitution of the 4-position with Me, i.e. 1,2,4,6 - tetramethyl - 3,5 - di(methoxycarbonyl) -1,4- dihydropyridine and its corresponding pyridinium perchlorate leads to cessation of hydride transfer: the same is true for the analogous 4-phenyl (and substituted phenyl) compounds. However, these 1,4-dihydropyridines are capable of transferring hydride at reasonable temperatures to less highly substituted pyridinium salts. Activation parameters for some of these hydride transfers have been determined, mechanistic conclusions are presented, and the consequences of these observations for experiments with “model” NADH compounds are discussed. 相似文献
4.
Cristóbal García Karina Cabezas Santi Nonell Javier Morales Germán Günther Nancy Pizarro 《Photochemistry and photobiology》2014,90(1):73-78
The electronic nature of substituents attached to the 4‐aryl moiety of 1,4‐dihydropyridines strongly affects the photophysical and photochemical behavior of these family of compounds. The presence of an electron donor substituent on the 4‐aryl moiety (or the absence of electron‐withdrawing ones) modifies the luminescence lifetimes (τ < 100 ps) and diminishes the photodecomposition quantum yields. For electron‐withdrawing substituents, the photodegradation quantum yield is affected by the media, changing more than two orders of magnitude as the polarity is increased. Studies in micellar media allow us to conclude that 4‐aryl‐1,4‐dihydropyridines are located near to the interface; however, the surface charge of micelles has no effect on the photodegradation rate constant or the photoproducts profile. The main conclusion of this work is that the photolability of 4‐aryl‐1,4‐dihydropyridines can be significantly reduced by the incorporation of antioxidant moieties. 相似文献
5.
Enaminones in Heterocyclic Syntheses: Part 4. A New One‐Step Synthetic Route to Pyrrolo[3,4‐b]pyridine and Convenient Syntheses of 1,4‐Dihydropyridines and 1,1′‐(1,4‐Phenylene)bis(1,4‐dihydropyridine)
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Reactions of cyano olefins with (i) enamino imides afforded novel pyrrolo[3,4‐b]pyridines; (ii) enamino esters afforded new 1,4‐dihydropyridines; and (iii) bisenamino ester afforded new 1,1′‐(1,4‐phenylene)bis(1,4‐dihydropyridine). The new derivatives are planned as suggested drug candidates. 相似文献
6.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(8):593-599
The salts 3‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium saccharinate, C9H10F4NO+·C7H4NO3S−, (1), and 3‐[(2,2,3,3,3‐pentafluoropropoxy)methyl]pyridinium saccharinate, C9H9F5NO+·C7H4NO3S−, (2), i.e. saccharinate (or 1,1‐dioxo‐1λ6,2‐benzothiazol‐3‐olate) salts of pyridinium with –CH2OCH2CF2CF2H and –CH2OCH2CF2CF3meta substituents, respectively, were investigated crystallographically in order to compare their fluorine‐related weak interactions in the solid state. Both salts demonstrate a stable synthon formed by the pyridinium cation and the saccharinate anion, in which a seven‐membered ring reveals a double hydrogen‐bonding pattern. The twist between the pyridinium plane and the saccharinate plane in (2) is 21.26 (8)° and that in (1) is 8.03 (6)°. Both salts also show stacks of alternating cation–anion π‐interactions. The layer distances, calculated from the centroid of the saccharinate plane to the neighbouring pyridinium planes, above and below, are 3.406 (2) and 3.517 (2) Å in (1), and 3.409 (3) and 3.458 (3) Å in (2). 相似文献
7.
Marina Petrova Ruslan Muhamadejev Brigita Cekavicus Brigita Vigante Aiva Plotniece Arkadij Sobolev Gunars Duburs Edvards Liepinsh 《Heteroatom Chemistry》2014,25(2):114-126
A reaction of diethyl 2,4,6‐trimethyl‐1,4‐dihydropyridine‐3,5‐dicarboxylate with 1, 2, and more equivalents of N‐bromosuccinimide (NBS) in methanol was investigated by NMR spectroscopy at a temperature interval ranging from 25 to 40°C. The reaction was found to proceed through several steps. The structures of the intermediates diethyl 3‐bromo‐2,4,6‐trimethyl‐3,4‐dihydropyridine‐3,5‐dicarboxylate, diethyl 3‐bromo‐2‐methoxy‐2,4,6‐trimethyl‐1,2,3,4‐tetrahydropyridine‐3,5‐dicarboxylate, and diethyl 3,5‐dibromo‐2‐methoxy‐2,4,6‐trimethyl‐2,3,4,5‐tetrahydropyridine‐3,5‐dicarboxylate were identified by multinuclear (1H, 13C, and 15N) NMR spectral data. The optimal structures of all species participating in the reaction as well as changes in their relative energies along with the proposed pathway of the reaction were analyzed by quantum‐chemical calculations. The mechanism of bromination of diethyl 2,4,6‐trimethyl‐1,4‐dihydropyridine‐3,5‐dicarboxylate with NBS in methanol was found to favor the bromination in the 2,6‐methyl side chains as the only products in full agreement with experimental observations. 相似文献
8.
Alexandru C. Razus Liviu Birzan Oana Zaharia Cristian Enache 《Journal of heterocyclic chemistry》2008,45(4):1139-1147
9.
Maryam Mirza‐Aghayan Mahboubeh Khoshkameh Langrodi Mahshid Rahimifard Rabah Boukherroub 《应用有机金属化学》2009,23(7):267-271
An efficient synthesis of 1,4‐dihydropyridine derivatives has been achieved by the one‐pot cyclocondensation reaction of methyl 3‐aminocrotonate and a range of aldehydes in the presence of chlorotrimethylsilane as a promoter under solvent‐free conditions. The cyclocondenstion reaction requires a very short time and takes place in good to excellent yields. Furthermore iodotriethylsilane, generated in situ by the reaction of triethylsilane and methyl iodide in the presence of palladium chloride, has been investigated for the synthesis of 1,4‐dihydropyridine derivatives. This facile and efficient method affords high yields for the preparation of 1,4‐dihydropyridines at room temperature and short reaction times. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
10.
Thioether 4‐[(1′E,3′E)‐4′‐phenylsulfanyl‐1,3′‐butadienyl]pyridine 8 and sulfone 4‐(4′‐phenylsulfonyl‐1′,3′‐butadienyl)pyridine 14 were prepared by reaction of the carbanions derived from allylic thioether or allylic sulfone with isonicotinaldehyde. The reaction with the sulfonyl carbanion occurred at the α position and on heating the alcolate gave the dienic sulfone 14 . The corresponding pyridinium iodide 10 and 15 were prepared by reaction with methyl iodide, respectively, on pyridine derivates 8 and 14 . The dienic pyridinium thioether 10 showed a long wavelength absorption band centered at 420 nm. The reaction of dienic pyridinium sulfone 15 with thiophenol gave the dienic pyridinium thioether 10 by a nucleophilic vinylic substitution. The reaction of sulfone 15 with glutathione was of second order and the rate constant was 8.5 M?1s?1 at 30°C and pH 7, about 500 times smaller than the rate constant observed with (E)‐1‐methyl‐4‐(2‐methylsulfonyl‐1‐ethenyl)pyridinium iodide 1 . The dienic pyridinium thioether 10 was a negative solvatochrome. 相似文献
11.
Ricardo Salazar V. Pardo‐Jimenez P. A. Navarrete‐Encina J. A. Squella C. Camargo Luis J. Núñez‐Vergara 《国际化学动力学杂志》2012,44(12):810-820
The radical‐scavenging ability of synthesized C4‐phenolic‐substituted 1,4‐dihydropyridines (1,4‐DHPs) toward 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH?) and alkyl/alkylperoxyl ABAP‐derived radicals at pH 7.4 was assessed by UV–visible spectroscopy. Reactivity of 1,4‐DHPs toward DPPH? was measured by following the decay of the absorption corresponding to the radical λmax at 525 nm, permitting the calculation of EC50, tEC50, and antiradical efficiency values. Pseudo–first‐order kinetic rate constants for the reactivity between the C4‐phenolic‐substituted 1,4‐DHP compounds and alkyl/alkylperoxyl ABAP‐derived radicals were followed by the decrease in λmax at 356 nm corresponding to 1,4‐DHP moiety. C4‐phenolic‐substituted 1,4‐DHPs were more reactive toward alkyl free radicals than the other tested radicals. The 3,4,5‐trihydroxyphenyl‐1,4‐DHP was the most reactive derivative toward this radical with a kinetic rate constant value of 513.2 s?1. Also, this derivative was the most effective toward the DPPH? radical with the lowest EC50 value (5.08 µM). Comparative studies revealed that synthesized 1,4‐DHPs were more reactive than commercial 1,4‐DHPs. The scavenging mechanism involves the contribution of both pharmacophores, that is, hydroxyphenyl and 1,4‐DHP rings, which was supported by the identification of the reaction products. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 810–820, 2012 相似文献
12.
Reaction of ethyl 2‐(3‐pyridyl)acetate 4a or ethyl 2‐methyl‐2‐(3‐pyridyl)acetate 4b , with phenyl chloroformate or methyl chloroform ate, afforded the intermediate pyridinium salt 5 which undergoes regioselective nucleophilic attack at C‐4 upon reaction with a Grignard reagent in the presence of a cuprous iodide catalyst at ?23° to yield the corresponding ethyl 2‐[3‐(1‐phenoxy(methoxy)carbonyl‐4‐aryl(alkyl)‐1,4‐dihydropyridyl)]acetates 6a‐f in 64–96% chemical yield. No product arising from reaction of the ester substituent of the pyridinium salt 5 with the Grignard reagent was observed. The 1H nmr spectra of 6a‐f exhibited dual resonances for the 1,4‐dihydropyridyl H‐2, H‐5 and H‐6 protons at 25° in deuteriochloroform. These dual resonaces were attributed to two different rotameric configurations resulting from restricted rotation about the nitrogen‐to‐carbonyl carbamate bond due to its double bond character. Compound 6 generally exhibited superior analgesic and antiinflammatory activities, compared to the reference drugs aspirin and ibuprofen, respectively. These structure‐activity correlations indicate the 1,4‐dihydropyridyl ring system present in 6 is a suitable bioisostere for the aryl (heteroaryl) ring present in aryl(heteroaryl)acetic acid non‐steroidal antiinflammatory drugs. 相似文献
13.
Isao Yamaguchi Hideo Higashi Shunsuke Kimura Moriyuki Sato 《Helvetica chimica acta》2010,93(5):819-828
Diacetylenes (DAs) having a dipolar D‐π‐A structure (D=donor: amino group; π=π‐conjugation core; A=acceptor: pyridinium (Py) and bipyridinium (BPy) groups), i.e., 4 (APBPyDA) and 5 (APPyPyDA), or an A‐π‐A structure, i.e., 7 (DBPyDA) and 8 (PyDA(Cl)), were obtained by 1 : 1 and 1 : 2 reactions of 4,4′‐(buta‐1,3‐diyne‐1,4‐diyl)bis[benzenamine] (APDA; 3 ) with 1‐(2,4‐dinitrophenyl)‐1′‐hexyl‐4,4′‐bipyridinium bromide chloride (1 : 1 : 1) ( 1 ), 1‐(2,4‐dinitrophenyl)‐4‐(pyridin‐4‐yl)pyridinium chloride ( 2 ), or 1‐(2,4‐dinitrophenyl)pyridinium chloride ( 6 ) (Schemes 1 and 2). The anion‐exchange reactions of 8 with NaI and Li(TCNQ) (TCNQ?=2,2′‐(cyclohexa‐2,5‐diene‐1,4‐diylidene)bis[propanedinitrile] radical ion (1?)) yielded the corresponding I? and TCNQ? salts 9 (PyDA(I)) and 10 (PyDA(TCNQ)). Compounds 10 and 4 exhibited a UV/VIS absorption due to a charge transfer between the TCNQ? and the pyridinium groups and a strong solute–solvent interaction of a dipolar solute molecule in the polar environment, respectively. Compounds 8 – 10 exhibited photoluminescence in solution, whereas 4 and 7 did not because of the presence of the 4,4′‐bipyridinium quenching groups. Differential‐scanning‐calorimetry (DSC) measurements suggested that the DAs obtained in this study can be converted into poly(diacetylenes) by thermal polymerization. 相似文献
14.
Enantioselective Organocatalytic Reduction of β‐Trifluoromethyl Nitroalkenes: An Efficient Strategy for the Synthesis of Chiral β‐Trifluoromethyl Amines
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Elisabetta Massolo Prof. Maurizio Benaglia Manuel Orlandi Dr. Sergio Rossi Giuseppe Celentano 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(9):3589-3595
An efficient organocatalytic stereoselective reduction of β‐trifluoromethyl‐substituted nitroalkenes, mediated by 3,5‐dicarboxylic ester‐dihydropyridines (Hantzsch ester type), has been successfully developed. A multifunctional thiourea‐based (S)‐valine derivative was found to be the catalyst of choice, promoting the reaction in up to 97 % ee. The methodology has been applied to a wide variety of substrates, leading to the formation of differently substituted precursors of enantiomerically enriched β‐trifluoromethyl amines. The mechanism of the reaction and the mode of action of the metal‐free catalytic species were computationally investigated; on the basis of DFT transition‐state (TS) analysis, a model of stereoselection was also proposed. 相似文献
15.
V. Padmavathi A. Balaiah T. V. Ramana Reddy B. Jagan Mohan Reddy D. Bhaskar Reddy 《Heteroatom Chemistry》2003,14(6):513-517
Novel spiro heterocycles ( 5–12 ) were obtained by the cyclocondensation of 2,6‐diaryl‐4,4‐dimethoxycarbonyl‐/4‐cyano‐4‐ethoxycarbonyl‐1,4‐dihydropyridines( 3/4 ) with hydrazine hydrate, hydroxylamine hydrochloride, urea, and thiourea. All the compounds were characterized by IR, 1H NMR, and 13C NMR spectral data.© 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:513–517, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10183 相似文献
16.
Dr. Virginie Liautard Damien Jardel Clotilde Davies Muriel Berlande Dr. Thierry Buffeteau Dr. Dominique Cavagnat Dr. Frédéric Robert Dr. Jean‐Marc Vincent Prof. Dr. Yannick Landais 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(43):14532-14539
Enantioselective aldol reactions between substituted pyridine carbaldehydes and α‐ketoacids were shown to provide isotetronic acids or their corresponding pyridinium salts, depending on the nature of the substituents on the pyridine ring. The pyridinium salts were generated through nucleophilic attack of the pyridine nitrogen atom onto the reactive keto functional group. Moderate‐to‐good yields of both compounds were typically obtained and high levels of enantioselectivity were observed by using benzimidazole pyrrolidine I as a catalyst. Hydrogenation of the resulting pyridinium salts led to new indolizidines with high ee values and diastereocontrol. X‐ray diffraction studies allowed the determination of the relative configuration of the products. Finally, DFT calculations were performed to rationalize the divergent pathway as a function of the pyridine substituents. 相似文献
17.
Wiesaw Prukaa Dorota Prukaa Maciej Kubicki 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(5):o269-o271
The crystal structures of two (E)‐stilbazolium salts, namely 1‐(2‐chlorobenzyl)‐4‐[(E)‐2‐(3‐hydroxyphenyl)ethenyl]pyridinium chloride hemihydrate, C20H17ClNO+·Cl−·0.5H2O, (I), and 1‐(2‐bromobenzyl)‐4‐[(E)‐2‐(3‐hydroxyphenyl)ethenyl]pyridinium bromide hemihydrate, C20H17BrNO+·Br−·0.5H2O, (II), are isomorphous; the isostructurality index is 99.3%. In both salts, the azastyryl fragments are almost planar, while the rings of the benzyl groups are almost perpendicular to the azastyryl planes. The building blocks of the structures are twofold symmetric hydrogen‐bonded systems of two cations, two halide anions and one water molecule, which lies on a twofold axis. In the crystal structure, these blocks are connected by means of weaker interactions, viz. van der Waals, weak hydrogen bonding and stacking. This study illustrates the robustness of certain supramolecular motifs created by a spectrum of intermolecular interactions in generating these isomorphous crystal structures. 相似文献
18.
Irradiation of HX (X=CF3SO3 or CF3CO2) salts of 1‐aryl‐4‐pyridylbutadienes 1 a – 1 c in the solid‐state afforded syn head‐to‐tail dimers in good yields among a number of possible dimers, whereas irradiation of the neutral substrates gave a complex mixture or no products. A comparison of the X‐ray crystal structures of the neutral compounds and the HX salts clarified that their orientation modes are head‐to‐head and head‐to‐tail, respectively. Moreover, while the distances between the two neighboring double bonds of the neutral compounds are relatively far apart from each other, those of HX salts are close together, satisfying Schmidt's requirement. These findings suggested that cation‐π interactions between the pyridinium and aromatic rings are effective for the preorientation of the HX salts of substrates, leading to photodimers in high regio‐ and stereoselectivities. 相似文献
19.
Marc Renom‐Carrasco Piotr Gajewski Dr. Luca Pignataro Prof. Johannes G. de Vries Prof. Umberto Piarulli Prof. Cesare Gennari Dr. Laurent Lefort 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(28):9528-9532
The use of an equivalent amount of an organic base leads to high enantiomeric excess in the asymmetric hydrogenation of N‐benzylated 3‐substituted pyridinium salts into the corresponding piperidines. Indeed, in the presence of Et3N, a Rh‐JosiPhos catalyst reduced a range of pyridinium salts with ee values up to 90 %. The role of the base was elucidated with a mechanistic study involving the isolation of the various reaction intermediates and isotopic labeling experiments. Additionally, this study provided some evidence for an enantiodetermining step involving a dihydropyridine intermediate. 相似文献
20.
Aleksei B. Sheremetev Igor L. Yudin Nadezhda V. Palysaeva Kyrill Yu. Suponitsky 《Journal of heterocyclic chemistry》2012,49(2):394-401
The annulation reaction of vinamidinium salt containing nitrofurazanyl moiety at the β‐position gives access to the corresponding pyrazole. At nitration, two nitro groups were installed to the pyrazole ring. The synthesized 3‐(3,5‐dinitropyrazol‐4‐yl)‐4‐nitrofurazan 13 is strong NH acid and a new family energetic salts was prepared by direct neutralization with high nitrogen bases. Compound 13 crystallizes in the monoclinic space group P21/c, and charaterized by high density of 1.979 g/cm3 (at 100 K). J. Heterocyclic Chem., (2012). 相似文献