共查询到20条相似文献,搜索用时 93 毫秒
1.
Tom R. Wendland Brian S. Muntean Jaskiran Kaur Jhindan Mukherjee Jie Chen Xinxuan Tan Dinesh Attygalle Robert W. Collins Jon R. Kirchhoff L. M. Viranga Tillekeratne 《Electroanalysis》2011,23(10):2275-2279
Thiolated o‐quinone‐capped electrocatalysts modeled on the naturally occurring o‐quinone cofactor pyrroloquinoline quinone (PQQ) were designed and synthesized for the development of biosensor devices. The o‐quinone‐capped electrocatalysts self assembled on gold electrodes through a thiolated phenyleneethynylene linkage to form a monolayer less than 2 nm in thickness. Cyclic voltammetric measurements demonstrated reversible electrochemical properties between the quinone and hydroquinone forms of the head group. In an amperometric sensing mode, the modified electrodes reproducibly detected ethanethiol at micromolar levels demonstrating their robust electrocatalytic activity toward thiols. Their redox cycling and electrocatalytic properties show promise for detection of biologically important thiols and other nucleophiles. 相似文献
2.
Dmitri V. Kravchenko Volodymyr M. Kysil Alexey P. Ilyn Sergey E. Tkachenko Sergey Maliarchouk Ilya M. Okun 《合成通讯》2013,43(7):911-917
The article describes an effective synthesis and chemical transformations of 6‐(morpholine‐4‐sulfonyl)‐2,3,4‐quinolinetricarboxylic acid. The key step is the Pfitzinger reaction of 3,3‐dichloro‐2‐oxo‐2,3‐dihydro‐1H‐indole with diethyl 2‐oxosuccinate. Selective 2‐decarboxylation of the tricarboxylic acid followed by reaction of the resulting anhydride with a primary amine led to the formation of the 1,3‐dioxo‐2,3‐dihydro‐1H‐pyrrolo[3,4‐c]quinoline scaffold with interesting pharmacological activity. 相似文献
3.
Péter Csomós Lajos Fodor Antal Csámpai Pál Sohár 《Journal of heterocyclic chemistry》2011,48(5):1079-1084
We report a convenient approach for the synthesis of a new ring system: 4,5‐dihydro‐1,3‐thiazino[5,4‐b]indoles. The procedure involves the use of Lawesson's reagent in the presence of silica to achieve the one‐step ring‐closure reactions of 2‐benzoylamino‐3‐hydroxymethylindole intermediates to furnish 4,5‐dihydro‐2‐aryl‐1,3‐thiazino[5,4‐b]indoles. 2‐Phenylimino‐1,3‐thiazino[5,4‐b]indoles were obtained via the corresponding 3‐phenylthiourea‐2‐carboxylic acid ester derivatives by chemoselective reduction of the ester group, followed by ring closure under acidic conditions. The structures of the novel products were elucidated by IR, 1H‐NMR, and 13C‐NMR spectroscopy, including 2D‐HMQC, 2D‐HMBC, and DEPT measurements. J. Heterocyclic Chem., (2011). 相似文献
4.
《Bioelectrochemistry and bioenergetics (Lausanne, Switzerland)》1990,23(3):227-238
The voltammetric and spectroscopic properties of pyrroloquinoline quinone (PQQ) have been investigated in the pH range from 5 to 13.5. PQQ gives a reversible cyclic voltammogram at the mercury electrode, which is ascribed to a two-step one-electron redox reaction of the o-quinone moiety. Digital simulation analysis of the reversible voltammogram made it possible to evaluate the standard redox potentials of the PQQ/pyrroloquinoline semiquinone (PQQsem) and PQQsem/pyyroloquinoline quinol (PQQred) couples. From the redox potential vs. pH relationships, the acid dissociation constants of PQQ, PQQsem, and PQQred have also been determined. The absorption and electron spin resonance spectroscopic properties are explained by the acid-base and redox equilibria proposed here. 相似文献
5.
The novel 6‐ethyl‐4‐hydroxy‐2,5‐dioxo‐5,6‐dihydro‐2H‐pyrano[3,2‐c]quinoline‐3‐carboxaldehyde ( 2 ) was efficiently synthesized from Vilsmeier–Haack formylation of 3‐(1‐ethy1‐4‐hydroxy‐2‐oxo‐(1H)‐quinolin‐3‐yl)‐3‐oxopropanoic acid ( 1 ). The aldehyde 2 was allowed to react with some nitrogen nucleophiles producing a variety of hydrazones 3 – 7 . Reaction of aldehyde 2 with hydrazine hydrate and hydroxylamine hydrochloride afforded pyrazole and isoxazole annulated pyrano[3,2‐c]quinoline‐2,5(6H)‐dione, respectively. The reactivity of aldehyde 2 was examined toward some active methylene nitrile, namely, malononitrile, ethyl cyanoacetate, and cyanoacetamide leading to 2‐iminopyrano[2′,3′:4,5]pyrano[3,2‐c]quinolines 10 – 12 , respectively. Also, some novel pyrazolo[4″,3″:5′,6′]pyrano[2′,3′:4,5]pyrano[3,2‐c]quinolines ( 13 , 14 ) and thiazolo[5″,4″:5′,6′]pyrano[2′,3′:4,5]pyrano[3,2‐c]quinolines ( 15 , 16 ) were synthesized. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data. 相似文献
6.
Ethyl 1‐ethyl‐7‐methyl‐4‐oxo‐1,4‐dihydro[1,8]naphthyridine‐3‐carboxylate ( 1 ), precursor of nalidixic acid, has been converted in two steps through ([1,8]naphthyridin‐3‐yl)carbonylguanidine derivatives into substituted pyrimido[4,5‐b] and [5,4‐c][1,8]naphthyridines. 相似文献
7.
Structural,Magnetic, and Computational Correlations of Some Imidazolo‐Fused 1,2,4‐Benzotriazinyl Radicals 下载免费PDF全文
Dr. Christos P. Constantinides Dr. Andrey A. Berezin Dr. Maria Manoli Dr. Gregory M. Leitus Georgia A. Zissimou Prof. Jeremy M. Rawson Dr. Panayiotis A. Koutentis 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(18):5388-5396
1,3,7,8‐Tetraphenyl‐4,8‐dihydro‐1H‐imidazolo[4,5g][1,2,4]benzotriazin‐4‐yl ( 5 ), 8‐(4‐bromophenyl)‐1,3,7‐triphenyl‐4,8‐dihydro‐1H‐imidazolo[4,5g][1,2,4]benzotriazin‐4‐yl ( 6 ), and 8‐(4‐methoxyphenyl)‐1,3,7‐triphenyl‐4,8‐dihydro‐1H‐imidazolo[4,5g][1,2,4]benzotriazin‐4‐yl ( 7 ) were characterized by using X‐ray diffraction crystallography, variable‐temperature magnetic susceptibility studies, and DFT calculations. Radicals 5 – 7 pack in 1 D π stacks made of radical pairs with alternate short and long interplanar distances. The magnetic susceptibility (χ vs. T) of radicals 5 and 6 exhibit broad maxima at (50±2) and (50±4) K, respectively, and are interpreted in terms of an alternating antiferromagnetic Heisenberg linear chain model with average exchange‐interaction values of J=?31.3 and ?35.4 cm?1 (gsolid=2.0030 and 2.0028) and an alternation parameter a=0.15 and 0.38 for 5 and 6 , respectively. However, radical 7 forms 1 D columns of radical pairs with alternating distances; one of the interplanar distances is significantly longer than the other, which decreases the magnetic dimensionality and leads to discrete dimers with a ferromagnetic exchange interaction between the radicals (2J=23.6 cm?1, 2zJ′=?2.8 cm?1, gsolid=2.0028). Magnetic exchange‐coupling interactions in 1,2,4‐benzotriazinyl radicals are sensitive to the degree of slippage and inter‐radical separation, and such subtle changes in structure alter the fine balance between ferro‐ and antiferromagnetic interactions. 相似文献
8.
Stephen P. Stanforth 《Journal of heterocyclic chemistry》2005,42(4):723-725
The 2,3‐dihydro‐7‐methyl‐1H,5H‐pyrido[3,2,1‐ij]quinoline‐1,5‐dione derivatives 9 and 10 were prepared from 3‐(5,7‐dimethoxy‐4‐methyl‐2‐oxo‐2H‐quinolin‐1‐yl)propionitrile ( 6 ). Cyclodehydration of the amide 8 gave 1,2‐dihydro‐7,9‐dimethoxy‐6‐methylpyimido[1,2‐a]quinolin‐3‐one ( 11 ). 相似文献
9.
Agata Kowalczyk Anna Maria Nowicka Rafal Jurczakowski Pawel Niedzialkowski Tadeusz Ossowski Zbigniew Stojek 《Electroanalysis》2010,22(1):49-59
Interactions of dsDNA and ssDNA, at the surface of gold and silver electrodes, with three novel anthraquinone derivatives: 3‐(9′,10′‐dioxo‐9′,10′‐dihydro‐anthracen‐1‐yl)‐7,11‐di(carboxymethyl)‐3,7,11‐triazatridecanedioic acid, (AQ‐1); 1‐(9′,10′‐dioxo‐9′,10′‐dihydro‐anthracen‐1yl)‐9‐carboxymethyl‐5‐methyl‐1,5,9‐triazaundecanoicacid, (AQ‐2); and N‐(2‐(9,10‐dioxo‐9,10‐dihydro‐anthracen‐1‐ylamino)ethyl)‐2‐(1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecan‐7‐yl)acetamide, (AQ‐3) are studied. These derivatives are well soluble in water and phosphate buffer solutions. The square wave voltammetric behavior of these redox indicators is described and the parameters of interactions with DNA are reported. It is also pointed out that these compounds can be employed as the hybridization indicators. The difference in the binding ability of the particular redox indicator to single and double stranded DNA can be used for the detection of the complementary nucleic acids. 相似文献
10.
Parallel syntheses of 2-hydro-, 2-methyl-, and 2-methoxycarbonylimidazo-7,9-dimethoxycarbonyl analogues of the oxidation-reduction cofactor pyrroloquinoline quinone [4,5-dihydro-4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid] have been developed. The properties of the imidazolo analogues in relation to the corresponding pyrrole analogues will be important in assessing the origins of catalysis and biological activity in the cofactor, which has recently been shown to be a vitamin. 相似文献
11.
Ondřej Rudolf Vladimír Mrkvička Antonín Lyčka Michal Rouchal Antonín Klásek 《Helvetica chimica acta》2012,95(8):1352-1372
The Riemschneider reaction of 3‐thiocyanatoquinoline‐2,4(1H,3H)‐diones with conc. H2SO4 was investigated. Using different reaction conditions, 13 types of reaction products were isolated. Compounds bearing a Me, Et, or Bu group at C(3) afforded mainly [1,3]thiazolo[5,4‐c]quinoline‐2,4‐diones and 1,9b‐dihydro‐9b‐hydroxythiazolo[5,4‐c]quinoline‐2,4‐diones. In the case of the 3‐Bu derivatives of the starting compounds, C‐debutylation was also observed. If a Bn group is present at C(3), rapid C‐debenzylation of the starting thiocyanates occurred, yielding [1,3]oxathiolo[4,5‐c]quinoline‐2,4‐diones, and mixtures of mono‐, di‐, and trisulfides derived from 4‐hydroxy‐3‐sulfanylquinoline‐2‐ones. The reaction mechanism of all of the transformations is discussed. All new compounds were characterized by IR, 1H‐ and 13C‐NMR, and EI and ESI mass spectra, and in some cases, 15N‐NMR spectra were also used to characterize new compounds. 相似文献
12.
New Synthesis of Diazepino[3,2,1‐ij]quinoline and Pyrido[1,2,3‐de]quinoxalines via Addition–Elimination Followed by Cycloacylation 下载免费PDF全文
Pier Giovanni Baraldi Emanuela Ruggiero Mojgan Aghazadeh Tabrizi 《Journal of heterocyclic chemistry》2014,51(1):101-105
This paper describes a convenient and efficient synthesis of new fused tricyclic diazepino[3,2,1‐ij]quinolines and substituted pyrido[1,2,3‐de]quinoxalines. o‐Phenylenediamines are transformed in the tricycle nucleus in only a few‐step synthetic sequence to produce ethyl 2,8‐dioxo‐1,2,3,4‐tetrahydro‐8H [1,4]diazepino[3,2,1‐ij]quinoline‐7‐carboxylate, ethyl 8‐oxo‐1,2,3,4‐tetrahydro‐8H‐[1,4]diazepino[3,2,1‐ij]quinoline‐7‐carboxylate and ethyl 2,7‐dioxo‐2,3‐dihydro‐1H,7H‐pyrido[1,2,3‐de]quinoxaline‐6‐carboxylate. The method is economical and simple to perform. 相似文献
13.
This article reports direct electrocatalytic oxidation of cysteine (CySH) and cystine (CyS‐SCy) at an inexpensive Nafion/lead oxide‐manganese oxide combined catalyst in physiological pH. The synthesized lead oxide‐manganese oxide material is simply mixed with Nafion in the form of cast solution and modified on a disposable screen‐printed carbon electrode (designated as SPE/Nf‐PMO) for biosensing application. Electrochemical study with a standard redox couple of quinone/hydroquinone demonstrates an enhanced current response at the combined catalyst compared to its individual component. Surface characterization further provides information regarding the structural morphology of the catalyst to its catalytic performance. Direct electrocatalytic oxidation signals are observed at +0.75 and +1.20 V vs. Ag/AgCl for cysteine and cystine, respectively, at the SPE/Nf‐PMO. To extend the applicability, we further apply the proposed system for the detection of cysteine and cystine by flow injection analysis (FIA). Under optimized conditions, the detection limit (S/N=3) is 0.43 μM and 0.33 μM for cysteine and cystine, respectively. 相似文献
14.
3‐Alkyl/aryl‐3‐ureido‐1H,3H‐quinoline‐2,4‐diones ( 2 ) and 3a‐alkyl/aryl‐9b‐hydroxy‐3,3a,5,9b‐tetrahydro‐1H‐imidazo[4,5‐c]quinoline‐2,4‐diones ( 3 ) react in boiling concentrated HCl to give 5‐alkyl/aryl‐4‐(2‐aminophenyl)‐1,3‐dihydro‐2H‐imidazol‐2‐ones ( 6 ). The same compounds were prepared by the same procedure from 2‐alkyl/aryl‐3‐ureido‐1H‐indoles ( 4 ), which were obtained from the reaction of 3‐alkyl/aryl‐3‐aminoquinoline‐2,4(1H,3H)‐diones ( 1 ) with 1,3‐diphenylurea or by the transformation of 3a‐alkyl/aryl‐9b‐hydroxy‐3,3a,5,9b‐tetrahydro‐1H‐imidazo[4,5‐c]quinoline‐2,4‐diones ( 3 ) and 5‐alkyl/aryl‐4‐(2‐aminophenyl)‐1,3‐dihydro‐2H‐imidazol‐2‐ones ( 6 ) in boiling AcOH. The latter were converted into 1,3‐bis[2‐(2‐oxo‐2,3‐dihydro‐1H‐imidazol‐4‐yl)phenyl]ureas ( 5 ) by treatment with triphosgene. All compounds were characterized by 1H‐ and 13C‐NMR and IR spectroscopy, as well as atmospheric pressure chemical‐ionisation mass spectra. 相似文献
15.
Vladimír Mrkvička Antonín Lyčka Robert Vícha Antonín Klásek 《Helvetica chimica acta》2011,94(1):78-91
3‐Hydroxyquinoline‐2,4‐diones 1 react with isocyanates to give novel 1,2,3,4‐tetrahydro‐2,4‐dioxoquinolin‐3‐yl (alkyl/aryl)carbamates 2 and/or 1,9b‐dihydro‐9b‐hydroxyoxazolo[5,4‐c]quinoline‐2,4(3aH,5H)‐diones 3 . Both of these compounds are converted, by boiling in cyclohexylbenzene solution in the presence of Ph3P or 4‐(dimethylamino)pyridine, to give 3‐(acyloxy)‐1,3‐dihydro‐2H‐indol‐2‐ones 8 . All compounds were characterized by IR, and 1H‐ and 13C‐NMR spectroscopy, as well as by EI mass spectrometry. 相似文献
16.
《Electroanalysis》2004,16(23):1938-1943
An organically modified sol‐gel glass (ORMOSIL) encapsulating pyrroloquinoline quinone (PQQ)‐modified electrode for the rapid, sensitive and simple determination of thiol‐containing compounds such as cysteine and glutathione is reported. The effect of applied potential, nature of thiol compound and pH on the response of the sensor was examined and optimum conditions were determined. The electrochemical responses and detection limits were found to be sensitive to the nature of thiols and pH. The electrochemical responses for cysteine and glutathione at an applied potential of ?0.2 V (vs. Ag/AgCl) were found to be linear with detection limits of 18 nM for cysteine and 36 nM for glutathione at pH 3.5, whereas the detection limits at pH 8.5 were 0.5 μM for cysteine and 1 μM for glutathione. The electrode retained 95% of the original response for 7 days when stored at 4 °C. The ORMOSIL‐encapsulated PQQ was also characterized by spectrophotometry. The absorbance measurement using 5,5′‐dithiobis(2‐nitrobenzoic acid) at 412 nm justify the PQQ‐mediated oxidation of glutathione whereas fluorescence measurements (excitation wavelength=380 nm; emission wavelength=480 nm) justify the successful encapsulation of PQQ in ORMOSIL matrix. 相似文献
17.
Antonín Klsek Michal Kov Ignc Hoza Antonín Ly
ka Michal Hol
apek 《Journal of heterocyclic chemistry》2006,43(5):1251-1260
1‐Substituted 3‐alkyl/aryl‐3‐amino‐1H,3H‐quinoline‐2,4‐diones ( 6 ) react with nitrourea to give 3‐ureido‐1H,3H‐quinoline‐2,4‐diones ( 10 ), 9b‐hydroxy‐3,3a,5,9b‐tetrahydro‐1H‐imidazo[4,5‐c]quinoline‐2,4‐diones ( 11 ), and 3,3a‐dihydro‐5H‐imidazo[4,5‐c]quinoline‐2,4‐diones ( 12 ). Compounds 11 were dehydrated to 12 by the action of phosphorus pentoxide. All three types of compounds rearrange in boiling acetic acid to give three different types of products of molecular rearrangement. A proposed reaction mechanism is discussed. 相似文献
18.
Mahmoud Al‐Talib Hasan Tashtoush Areej Al‐Ghoul Burkhard Ziemer Ulrich Koert 《Journal of heterocyclic chemistry》2005,42(2):287-288
Phenylmalonic acid dihydrazide reacted with 2,4‐pentanedione to give, unexpectedly, 5,7‐dimethyl‐1,3‐dioxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazolo[1,2‐a]pyrazole‐4‐ylium 5. The structure of the product is confirmed by X‐ray crystallography. 相似文献
19.
Kamal M. El‐Shaieb 《中国化学会会志》2007,54(5):1353-1358
When 2,3‐dichloro‐1,4‐naphthoquinone (DCHNQ) ( 1 ) is allowed to react with 1‐phenylbiguanide (PBG) ( 2 ), 4‐chloro‐2,5‐dihydro‐2,5‐dioxonaphtho[1,2‐d]imidazole‐3‐carboxylic acid phenyl amide ( 4 ), 6‐chloro‐8‐phenylamino‐9H‐7,9,11‐triaza‐cyclohepta[a]naphthalene‐5,10‐dione ( 5 ) and 4‐dimethyl‐amino‐5,10‐dioxo‐2‐phenylimino‐5,10‐dihydro‐2H‐benzo[g]quinazoline‐1‐carboxylic acid amide ( 6 ) were obtained. While on reacting 1 with 2‐guanidinebenzimidazole (GBI) ( 3 ) the products are 3‐(1H‐benzoimidazol‐2‐yl)‐4‐chloro‐3H‐naphtho[1,2‐d]imidazole‐2,5‐dione ( 7 ) and 3‐[3‐(1H‐benzoimidazol‐2‐yl)‐ureido]‐1,4‐dioxo‐1,4‐dihydronaphthalene‐2‐carboxylic acid dimethylamide ( 8 ). 相似文献
20.
Polycyclic N‐Heterocyclic Compounds. Part 75: Synthesis of 2,4‐Disubstituted 5,6‐dihydro[1]benzoxepino[5,4‐d]pyrimidines and 12‐Substituted 1,2,4,5‐Tetrahydro[1]benzoxepino[4,5‐e]imidazo[1,2‐c]pyrimidines as Potential Antiplatelet Aggregators 下载免费PDF全文
Kensuke Okuda Yuko Yamamoto Takashi Hirota Kenji Sasaki 《Journal of heterocyclic chemistry》2014,51(4):972-981
Libraries of tricyclic 2‐substituted 4‐alkylamino‐5,6‐dihydro[1]benzoxepino[5,4‐d]pyrimidines and tetracyclic 12‐substituted 1,2,4,5‐tetrahydro[1]benzoxepino[4,5‐e]imidazo[1,2‐c]pyrimidines were synthesized as part of our research to develop new effective antiplatelet drugs. Several alkyl and aryl groups were used as substituents at the 2‐position. Evaluation of the effects of the newly synthesized compounds on collagen‐induced platelet aggregation revealed several promising antiplatelet candidates with potencies superior to aspirin. 相似文献