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1.
Salo Gronowitz Anna-Britta Hrnfeldt Ecaterina Temciuc 《Journal of heterocyclic chemistry》1993,30(2):533-535
The 3-position of dithieno[3,4-b:3′,2′-d]pyridine was found to be most reactive with regard to lithiation, bromination and halogen-metal exchange. The lithium compounds were trapped as the formyl derivatives by reaction with N,N-dimethylformamide. 相似文献
2.
The pyridine and quinoline derivatives 2, 3 , and 6 with an activated methylene group atα-position in respect to the ring nitrogen atom were converted with 1, 8 , or 9 into fused pyrido[1,2-a]pyridine derivatives 4, 5, 7 , and 10 . In an analogous manner were the aminopyridines 16 and 17 transformed with thiazolone 9 into pyrido[1,2-a]pyrimidine derivatives 20, 21, 25 , and 26 . 相似文献
3.
Richard J. Sundberg D. J. Dahlhausen G. Manikumar B. Mavunkel Atanu Biswas V. Srinivasan Fred King Philip Waid 《Journal of heterocyclic chemistry》1988,25(1):129-137
A series of substituted 2-aryl imidazo[1,2-a]pyridines has been prepared in which a variety of substituents are introduced on the 4′-position of the phenyl ring and on the 3, 5 , 6 or 7 position of the heterocyclic ring. Most examples have acetamido, bromo, cyano, or formyl substituents at the 4′-position. Analogous imidazo-[2,1-b]fhiazoles and imidazo[1,2-a]pyrimidines have also been prepared. Another series of compounds consisting of 4′-formylphenoxymethyl derivatives of imidazole, the three positional isomers of pyridine, thiazole, benzimidazole and ring-substituted imidazo[1,2-a]pyridines has been prepared. 2-(4′-Formylphenylethenyl) derivatives of imidazole and imidazo[1,2-a]pyridine were also prepared. 相似文献
4.
Dr. Xiao-Jun Tang Yayun Wu Rong Zhao Dr. Xiaolong Kou Dr. Zaizai Dong Dr. Wei Zhou Dr. Zhen Zhang Prof. Dr. Weihong Tan Prof. Dr. Xiaohong Fang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(42):18544-18547
The photorelease of bioactive molecules has emerged as a valuable tool in biochemistry. Nevertheless, many important bioactive molecules, such as pyridine derivatives, cannot benefit from currently available organic photoremovable protecting groups (PPGs). We found that the inefficient photorelease of pyridines is attributed to intramolecular photoinduced electron transfer (PET) from PPGs to pyridinium ions. To alleviate PET, we rationally designed a strategy to drive the excited state of PPG from S1 to T1 with a heavy atom, and synthesized a new PPG by substitution of the H atom at the 3-position of 7-dietheylamino-coumarin-4-methyl ( DEACM ) with Br or I. This resulted in an improved photolytic efficiency of the pyridinium ion by hundreds-fold in aqueous solution. The PPG can be applied to various pyridine derivatives. The successful photorelease of a microtubule inhibitor, indibulin, in living cells was demonstrated for the potential application of this strategy in biochemical research. 相似文献
5.
O. Yu. Slabko A. V. Kachanov V. A. Kaminskii 《Russian Journal of Organic Chemistry》2012,48(9):1180-1186
Reactions of some 1,5-diketones with 2-aminobenzyl alcohol and 2-aminomethylaniline follow double cyclization scheme with formation of pyridobenzoxazine and pyridoquinazoline derivatives, respectively. Oxidative coupling of the cyclization products with CH acids occurs at the 4-position of the pyridine ring. 相似文献
6.
L. Bukowski Zofia Zwolska Ewa Augustynowicz-Kopeć 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):879-887
Abstract The reactions of 2-cyanomethyl-1-methyl-1H-imidazo[4,5-b]pyridine with isothiocyanates, nitroso compounds, acid chlorides, and thioglycolic acid were investigated. New imidazo[4,5-b]pyridine derivatives with various substituents in 2-position and derivatives of the new pyrrolo[2′,1′:2,3]imidazo[4,5-b]pyridine ring system were synthesized. The compounds obtained were tested in vitro for their tuberculostatic activity. 相似文献
7.
Rabab Boyaala Rachid Touzani Véronique Guerchais Jean-François Soulé Henri Doucet 《Tetrahedron letters》2017,58(33):3205-3208
We report herein on palladium-catalyzed direct arylation of (poly)fluorobenzene derivatives in the presence of 2-halopyridines for the one-step synthesis of 2-[(poly)fluorinated aryl]pyridine derivatives. The reactivity of 2-bromopyridines strongly dependents on its substituents at C6 position. The reaction proceeds nicely using a diphosphine palladium catalyst, and potassium pivalate/dimethylacetamide (PivOK/DMA) as catalytic system. The reaction was regioselective and occurred at the ortho-position of fluorine atoms. 相似文献
8.
Attila Sisak 《合成通讯》2013,43(24):3693-3702
2‐Aza‐1,3‐butadienes have been synthesized from carbonyl compounds and 1,1,1,3,3,3‐hexamethyl‐disilazane in the presence of cobalt‐containing catalysts. The best yields (up to 95%) were achieved in the case of aldehydes branched in the α-position and 2-methylcyclohexanone. In the case of two α,β‐unsaturated ketones, pyridine derivatives were found as the main products. 相似文献
9.
Ludovic Jean Michael Pouliquen Jérôme Blanchet Marie-Claire Lasne Jacques Rouden 《中国科学:化学(英文版)》2010,53(9):1907-1913
Enantiopure 2-(dicyclohexylphosphino)-1,1′-biphenyl derivatives substituted in the 2′-position by a chiral amino group were prepared. For the compound bearing an acyclic chiral chain, the key step was a Suzuki coupling between bromobenzeneboronic acid and N-Boc-iodoaniline whereas an aromatic nucleophilic substitution allowed the introduction of a chiral pyrrolidine in the 2′-position of the biphenyl backbone. The efficiency of the P,N-biphenyl pyrrolidine derivatives as ligands in Pd-catalyzed arylaminations compares well with that of DavePhos ligand. 相似文献
10.
Mollenhauer D Floss J Reissig HU Voloshina E Paulus B 《Journal of computational chemistry》2011,32(9):1839-1845
Interaction of gold with pyridine and its derivatives was studied by means of different wavefunction-based correlation methods and standar DFT functionals as well as accounting for dispersion correction. Comparison of the calculated binding energies with benchmark CCSD(T)results allows us to find an appropriate computational method, when considering the two structures reflecting the interaction of gold with the lone pair at nitrogen, on the one hand, and with the π-system of pyridine, on the other hand. Additional binding sites were evaluated, when performing potential energy surface calculations and structure optimizations. The enhancement of the interaction energy due to donor substituents in the 4-position of the pyridine molecule has been investigated. 相似文献
11.
Homogeneous palladium catalyst suppressing Pd black formation in air oxidation of alcohols 总被引:1,自引:0,他引:1
Iwasawa T Tokunaga M Obora Y Tsuji Y 《Journal of the American Chemical Society》2004,126(21):6554-6555
In homogeneous catalyst systems, there is the persistent problem that metal aggregation and precipitation cause catalyst decomposition and considerable loss of catalytic activity. Pd black formation is a typical example. Pd catalysts are known to easily aggregate and form Pd black, although they realize a wide variety of useful reactions in organic synthesis. In order to overcome this intrinsic problem of homogeneous Pd catalysis, we explored a new class of Pd catalyst by adopting aerobic oxidation of alcohols as a probe reaction. Herein we report a new catalyst system that suppresses the Pd black formation even under air and with a high substrate to catalyst molar ratio (S/C: more than 1000) in oxidation of alcohols. The novel pyridine derivatives having a 2,3,4,5-tetraphenylphenyl substituent and its higher dendritic unit at the 3-position of the pyridine ring were found to be excellent ligands with Pd(OAc)2 in the palladium-catalyzed air (balloon) oxidation of alcohols in toluene at 80 degrees C. Comparison with structurally related pyridine ligands revealed that introduction of the 2,3,4,5-tetraphenylphenyl substituent at the 3-position of pyridine ring effectively suppresses the Pd black formation, maintaining the catalytic activity for a long time to give aldehydes or ketones as products in high yields. 相似文献
12.
The enolate anions of 5-alkylbarbituric acids and isopropylidene alkylmalonates are demonstrated to readily displace chloro, pyridinio, and acetoxy substituents from the 4-position of simple pyridine derivatives under conditions in which the ring nitrogen carries a positive charge. 相似文献
13.
Toshikatsu Sata Yoriko Yamane Koji Matsusaki 《Journal of polymer science. Part A, Polymer chemistry》1998,36(1):49-58
Anion exchange membranes with pyridinum groups and various pyridinium derivative groups were prepared from a copolymer membrane composed of chloromethylstyrene and divinylbenzene, and pyridine and pyridine derivatives. The anion exchange membranes obtained showed excellent electrochemical properties in electrodialysis. The transport numbers of sulfate ions, bromide ions, nitrate ions, and fluoride ions relative to chloride ions were evaluated in connection with the species of a substituent and the position of the substituent in the pyridinium groups. In general, when a hydrophilic substituent (methanol groups) existed at the 2-position of the pyridinium groups, nitrate ions and bromide ions, which are less hydrated, permeated through the membranes with difficulty, and sulfate ions permeated selectively through the membranes. On the other hand, when hydrophobic groups, for example, ethyl groups, existed at the 2-position of the pyridinium groups, bromide ions and nitrate ionspermeated selectively through the membranes and fluoride ions had difficulty permeating through the membranes. The carbon number of the alkyl chain of 4-alkyl pyridinium groups also affected permeation of nitrate ions and bromide ions due to the change in hydrophilicity of the membranes. Though the hydration of the anions and the species of the substituent at the 2-position of the pyridinium groups were related to selective permeation of the anion through the membranes, permeation of sulfate ions was not as sensitive to the hydrophilicity of the membranes. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 49–58, 1998 相似文献
14.
Moustafa A. Gouda Ghada E. Abd El‐Ggani Moged A. Berghot Abd El‐Galil M. Khalil 《Journal of heterocyclic chemistry》2019,56(7):2036-2045
As a part of ongoing studies in developing new potent antioxidant agents, 2‐amino‐4‐(furan‐2‐yl)‐5,6‐dimethylnicotinonitrile 4 was utilized as a key intermediate for the synthesis of some new pyrimidines 5 and 11 , form (acet)amide 6 , 7 , urea and thiourea 9 , 10 , 1,8‐naphthyridines 12 , 13 , and 14 . Moreover, condensation of 4 with 5,5‐dimethyl‐1,3‐cyclohexanedione and cyclohexanone in ethanol furnished the pyridine derivatives 16 and 17 , respectively. Furthermore, refluxing of 4 with ethylenediamine in carbon disulfide afforded the 4,5‐dihydro‐1H‐imidazol‐2‐yl pyridine derivative 19 . In addition, refluxing of 4 with carbon disulfide and concentrated sulfuric acid furnished the pyridine derivatives 20 and 21 , respectively. The reaction of 4 with phenacyl chloride and ethyl chloroacetate in dimethylformamide in the presence of catalytic amount of triethylamine afforded the pyridine derivatives 22 and 23 , respectively. Finally, heating of 4 with 1‐phenyl‐3‐(piperidin‐1‐yl)propan‐1‐one hydrochloride in glacial acetic acid afforded phenylpropylamino pyridine derivative 24 . The structures of the newly synthesized compounds were confirmed by elemental analysis, IR, 1H‐NMR, and mass spectral data. Representative compounds of the synthesized products were evaluated as antioxidant agents. Compounds 8 , 19 , and 22 are promising compounds. 相似文献
15.
Tina VermondenDanuta Branowska Antonius T.M Marcelis Ernst J.R Sudhölter 《Tetrahedron》2003,59(27):5039-5045
Four different 4-functionalised pyridine-based ligands were synthesized with aminomethyl, oxazolinyl, pyrazolyl and methylimidazolyl groups at the 2- and 6-position. The nitrogens of these groups together with the pyridine nitrogen can act as terdendate ligands for metal ions. Synthetic handles on the 4-position of the pyridine group were introduced via ether or ester bonds leading to monofunctional, bifunctional and amphiphilic ligands. 相似文献
16.
Hill MS Kociok-Köhn G MacDougall DJ Mahon MF Weetman C 《Dalton transactions (Cambridge, England : 2003)》2011,40(46):12500-12509
Reactions of the β-diketiminato n-butyl magnesium complex, [HC{(Me)CN(2,6-(i)Pr(2)C(6)H(3))}(2)Mg(n)Bu], with a range of substituted pyridines and fused-ring quinolines in the presence of PhSiH(3) has been found to result in dearomatisation of the N-heterocyclic compounds. This reaction is proposed to occur through the formation of an unobserved N-heterocycle-coordinated magnesium hydride and subsequent hydride transfer via the C2-position of the heterocycle prior to hydride transfer to the C4-position and formation of thermodynamically-favoured magnesium 1,4-dihydropyridides. This reaction is kinetically suppressed for 2,6-dimethylpyridine while the kinetic product, the 1,2-dihydropyridide derivative, was isolated through reaction with 4-methylpyridine (4-methylpyridine), in which case the formation of the 1,4-dihyropyridide is prevented by the presence of the 4-methyl substituent. X-ray structures of the products of these reactions with 4-methylpyridine, 3,5-dimethylpyridine and iso-quinoline comprise a pseudo-tetrahedral magnesium centre while the regiochemistry of the particular dearomatisation reaction is determined by the substitution pattern of the N-heterocycle under observation. The compounds are all air-sensitive and exposure of the magnesium derivatives of dearomatised pyridine and 4-dimethylaminopyridine (DMAP) to air resulted in ligand rearomatisation and the formation of dimeric μ(2)-η(2)-η(2)-peroxomagnesium compounds which have also been subject to analysis by single crystal X-ray diffraction analysis. An unsuccessful extension of this chemistry to N-heterocycle hydrosilylation is suggested to be a consequence of the low basicity of the silane reagent in comparison to the pyridine substrates which effectively impedes any further interaction with the magnesium centres. 相似文献
17.
吡啶-2,6-二甲酸衍生物及其Tb(Ⅲ)和Eu(Ⅲ)配合物的合成与荧光性质 总被引:7,自引:0,他引:7
以吡啶-2,6-二甲酸(DPA)为起始物,合成了4-羟甲基吡啶-2,6-二甲酸(4-HMDPA)和4-(N,N-二羧甲基氨基)亚甲基吡啶-2,6-二甲酸(4-BMDPA)两种新型多功能配体,并制备了DPA,4-HMDPA及4-BMDPA的Tb(Ⅲ)和Eu(Ⅲ)配合物,对配合物的固体和溶液态的荧光性质进行了研究. 结果表明,在吡啶4位引入弱吸电子基团4-羟甲基会减弱稀土配合物的荧光强度; 在水溶液中稀土配合物与溶液的pH值有着密切的关联,中性水溶液中荧光强度较大; 分子偶极矩较小的溶剂中稀土配合物荧光强度较强. 表明4-BMDPA是较理想的稀土荧光敏化剂. 相似文献
18.
《Liquid crystals》2000,27(1):69-74
Supramolecular liquid crystalline polymeric complexes have been prepared by the complexation of 4-alkyloxybenzoic acid derivatives and polyamides containing a 2,6-diaminopyridine moiety. 4-Alkyloxybenzoic acids substituted by methoxy, methyl, and nitro groups at the 3-position are used for the complexation. These polymeric complexes behave as single component liquid crystalline polymers and exhibit stable and enantiotropic mesophases. In contrast, simple 4-alkyloxybenzoic acids having no substituent at the 3-position, do not form stable complexes with the polymers. For low molecular mass complexes derived from 2,6-bis(acylamino)pyridine and 4-alkyloxybenzoic acid derivatives, substituent effects are different from those for the polymeric system. In these cases, mesomorphic behaviour is observed only for the complexes based on the simple 4-alkyloxybenzoic acid and 4-alkyloxy-3-methylbenzoic acid. 相似文献
19.
20.
Synthesis of Pyrido[2′,3′: 3,4]pyrazolo[1,5‐a]pyrimidine,Pyrido[2′,3′:3,4]pyrazolo[5,1‐c][1,2,4]triazine,and Pyrazolyl Oxadiazolylthieno[2,3‐b]pyridine Derivatives
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Nora M. Rateb 《Journal of heterocyclic chemistry》2014,51(5):1349-1356
6‐(2‐Thienyl)‐4‐(trifluoromethyl)‐1H‐pyrazolo[3,4‐b]pyridine‐3‐amine reacted with different active methylene compounds to afford pyridopyrazolopyrimidine derivatives. On the other hand, it reacted with some halo compounds to give the imidazo[1′,2′:1,5]pyrazolo[3,4‐b]pyridine derivatives. Also, it diazotized to give the corresponding diazonium chloride that is coupled with several active methylene compounds to give the corresponding triazine derivatives. Furthermore, compound 3‐amino‐6‐(2(thienyl)‐4‐(trifluoromethyl)thieno[2,3‐b]pyridine‐2‐carbohydrazide reacted with some β‐dicarbonyl compounds and some sulfur‐containing compounds to afford the corresponding pyrazolyl oxadiazolylthieno[2,3‐b]pyridine derivatives. 相似文献