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A new, one-step procedure for the generation of azomethine ylides, 4 and 20, via chloroiminium salts, 3 and 19, is reported. The generation of the azomethine ylides was confirmed by their trapping with dimethyl acetylenedicarboxylate (DMAD) which, upon spontaneous 1,4-dehydrochlorination, gave the corresponding pyrroles 17 and 21. 相似文献
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Bharathi Avula Babu L. Tekwani Narayan D. Chaurasiya NP Dhammika Nanayakkara Yan‐Hong Wang Shabana I. Khan Vijender R. Adelli Rajnish Sahu Mahmoud A. Elsohly James D. McChesney Ikhlas A. Khan Larry A. Walker 《Journal of mass spectrometry : JMS》2013,48(2):276-285
Therapeutic efficiency and hemolytic toxicity of primaquine (PQ), the only drug available for radical cure of relapsing vivax malaria are believed to be mediated by its metabolites. However, identification of these metabolites has remained a major challenge apparently due to low quantities and their reactive nature. Drug candidates labeled with stable isotopes afford convenient tools for tracking drug‐derived metabolites in complex matrices by liquid chromatography‐tandem mass spectrometry (LC‐MS‐MS) and filtering for masses with twin peaks attributable to the label. This study was undertaken to identify metabolites of PQ from an in vitro incubation of a 1:1 w/w mixture of 13C6‐PQ/PQ with primary human hepatocytes. Acquity ultra‐performance LC (UHPLC) was integrated with QTOF‐MS to combine the efficiency of separation with high sensitivity, selectivity of detection and accurate mass determination. UHPLC retention time, twin mass peaks with difference of 6 (originating from 13C6‐PQ/PQ), and MS‐MS fragmentation pattern were used for phenotyping. Besides carboxy‐PQ (cPQ), formed by oxidative deamination of PQ to an aldehyde and subsequent oxidation, several other metabolites were identified: including PQ alcohol, predictably generated by oxidative deamination of PQ to an aldehyde and subsequent reduction, its acetate and the alcohol's glucuronide conjugate. Trace amounts of quinone‐imine metabolites of PQ and cPQ were also detected which may be generated by hydroxylation of the PQ/cPQ quinoline ring at the 5‐position and subsequent oxidation. These findings shed additional light on the human hepatic metabolism of PQ, and the method can be applied for identification of reactive PQ metabolites generated in vivo in preclinical and clinical studies. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Bakulev VA Berseneva VS Belskaia NP Morzherin YY Zaitsev A Dehaen W Luyten I Toppet S 《Organic & biomolecular chemistry》2003,1(1):134-139
A systematic study of the reactions of dimethyl acetylenedicarboxylate (DMAD) and methyl propynoate with 5-mercaptoazoles and pyridine-2-thiones has been carried out and as a result, a number of novel imidazo[1,5-b]thiazin-4-ones 6a,b, pyrazolo[1,5-b] thiazin-4-ones 15a-f, imidazo[1,5-b]thiazol-4-ones 7a,b and thiazolo[3,2-a]pyridines 21a-c have been prepared. The influence of the size of the ring of the starting "cyclic" thioamides on the size of the fused ring in the reaction products has been established. The preferred formation of a six-membered thiazine ring took place in the reactions of 5-mercaptoazoles. In contrast, the five membered thiazolidine ring is formed in reactions of pyridine-2-thiones. In both cases the product is a five-membered ring fused to a six-membered heterocycle. 相似文献
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I. V. Paramonov N. P. Belskaia V. A. Bakulev 《Chemistry of Heterocyclic Compounds》2003,39(10):1385-1395
The reaction of (arylhydrazono)cyanothioacetamides with chloro ketones and phenacyl bromides was studied. The products are either thiazoles or 4,5-dihydrothiophenes, depending on the starting thioamides and halo ketones. 相似文献
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Natalia P. Belskaia Tatyana G. Deryabina Alexandr V. Koksharov Mikhail I. Kodess Wim Dehaen Albert T. Lebedev Vasiliy A. Bakulev 《Tetrahedron letters》2007,48(52):9128-9131
3-Allyl- and 3-prop-1-ynylsulfanyl-2-arylazo-3-cycloalkylamino-acrylonitriles undergo cyclization under mild conditions to afford the novel heterocyclic systems 1,4,6,7,8,8a-hexahydropyrrolo[2,1-c][1,2,4]-triazine-4-thione, 1,4,6,7,9,9a-hexahydro-[1,4]oxazino[3,4-c][1,2,4]triazine and 1,6,7,8,9,9a-hexahydro-4H-pyrido[2,1-c][1,2,4]triazine via a number of consecutive pericyclic reactions. 相似文献
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Maria L. Kondratieva Natalia P. Belskaia Alexandr V. Koksharov Koen Robeyns Wim Dehaen Vasiliy A. Bakulev 《Tetrahedron》2007,63(14):3042-3048
The systematic study of oxidative cyclization of 3-hydrazono-1,3-dihydroindole-2-thiones has been carried out and a series of new 2H-[1,2,3]thiadiazolo[5,4-b]indoles has been prepared. The elaborated reaction represents an efficient method for the synthesis of fused 1,2,3-thiadiazoles. 相似文献
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Synthesis and Crystal Structure of 3,6-Bis(4-methyl-1,2,3-thiadiazol-5-yl)-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole 总被引:1,自引:0,他引:1
The compound 3,6-bis(4-methyl-1,2,3-thiadiazol-5-yl)-1,2,4-triazolo[3,4-b][1,3,4] thiadiazole(C9H6N8S3,Mr = 322.40) has been synthesized by the reaction of 4-amino-3-(4-methyl-1,2,3-thiadiazolyl)-5-mercapto-1,2,4-triazole with 4-methyl-1,2,3-thiadiazol-5-carboxylic acid and phosphorus oxychloride,and its structure was characterized by IR,1H NMR,EI-MS,elemental analysis and single-crystal X-ray diffraction.The crystal of the title compound belongs to monoclinic,space group C2/c with a = 2.0053(4),b = 1.3081(3),c = 1.0556(2) nm,β = 112.69(3)°,Z = 4,V = 2.5548(9) nm3,Dc = 1.676 g/cm3,μ = 0.582 mm-1,F(000) = 1312,R = 0.0546 and wR = 0.1523.X-ray analysis indicates that all rings are essentially planar in this molecule,and an intermolecular hydrogen bond C(9)-H(9)…N(2) and weak intramolecular interactions between S(1)…N(7),S(3)…N(1) and S(2)…N(4) are observed. 相似文献
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Unsteady flow in a semi-infinite contracting or expanding pipeis reinvestigated using long series analysis. The proposed seriesmethod is useful in analysing the problem for a moderately largeconstant ( = aa/, where a = a(t), the radius of the pipe isa function of time, a(t) is the velocity of the wall, and iskinematic viscosity). For positive values of (expansion ofthe pipe) accuracy of the series representing shear stress andpressure gradient is increased from = 2.89 to = 6.0 by extractingthe singularity followed by completion of the series. For negativevalues of (contraction of the pipe), we revert the series whichresults into the increase of the region of validity of the transposedseries from = -25.0 to = -2.89. Later we use Padé approximantsfor summing them. Also, the asymptotic solution for large valuesof is obtained and it agrees closely with pure numerical valuesof shear stress at the wall and pressure gradient. 相似文献
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