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排序方式: 共有148条查询结果,搜索用时 15 毫秒
1.
P. R. Latthe P. S. Shinge Bharati V. Badami P. B. Patil S. N. Holihosur 《Journal of Chemical Sciences》2006,118(3):249-256
3-[4-(Azidocarbonyl)]phenylsydnone (2) obtained from 3-(4-hydrazinocarbonyl) phenylsydnone (1) on Curtius rearrangement with alcohols, water and amines afforded the corresponding carbamates (3a-h), 4,4′-(sydnone-3-yl) diphenyl urea (4) and 4-(heterocyclyl)phenyl ureas (5a-l). Compounds (5a-l) on one-pot ring conversion yielded the 1,3,4-oxadiazolin-2-one derivatives (6a-l), which on reaction with N2H4 gave the 4-amino-1,2,4-triazolin-3-ones (7a-l). All these compounds exhibited moderate antimicrobial activity against the few microbes tested. The carbamates have been
found to be more toxic against fourth instar larvae ofAedes aegypti, in particular, then-butyl derivative (3e). 相似文献
2.
Fluoride effect on the palladium–phenanthroline catalyzed carbonylation of nitroarenes to carbamates
Michela Gasperini Fabio Ragaini Sergio Cenini Emma Gallo Simone Fantauzzi 《应用有机金属化学》2007,21(9):782-787
Fluorides promote the palladium–phenanthroline catalyzed carbonylation of nitroarenes to carbamates. The effect is more evident on the rate of the reaction at short reaction times, but a positive effect on selectivity is also observed under certain conditions. The effect is observed even under conditions under which chloride inhibits the reaction. Tetraethylammonium is a better countercation than sodium. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
3.
A. A. Bogolyubov N. B. Chernysheva V. V. Nesterov M. Yu. Antipin V. V. Semenov 《Chemistry of Heterocyclic Compounds》2004,40(8):992-1001
The composition and yields of the products from the reaction of 4,4-dialkyl-5-methylene-1,3-dioxolan-2-ones with amidines depend on the structure of the initial amidine and on the reaction conditions. 2-Aminopyridines lead to 3-substituted 4-hydroxy-4-methyloxazolidin-2-ones and 4-methylene-oxazolidin-2-ones and also to sym-carbamides. 2-Amino-4,6-dimethylpyrimidine leads to the corresponding 4-methyleneoxazolidin-2-one. 3-Aminothiazoles give linear oxourethanes and sym-carbamides. 相似文献
4.
Gololobov Yu. G. Galkin V. I. Petrovskii P. V. Linchenko O. A. Zueva E. M. Mubarakova L. G. Cherkasov R. A. Schmutzler R. Ernst L. Jones P. G. Freytag M. 《Russian Chemical Bulletin》2003,52(9):1920-1927
Studies by 1H NMR spectroscopy and X-ray diffraction analysis revealed hindered rotation of the aromatic substituent about the CAr—N bond in ortho-substituted (except for o-fluorine-substituted) phosphorus-containing carbamates. The energy barriers to rotation (G
c
) and coalescence temperatures (T
c) determined by the coalescence method increase with increasing volume of the ortho substituent. Conformations resulting from rotation of the ortho-substituted aryl group about the CAr—N bond were analyzed by quantum-chemical methods, potential curves were constructed, and differences between the conformational energies and the heights of rotation barriers were estimated. The theoretical rotation barriers change in parallel with the experimental values of G
c
; however, the theoretical values are much smaller in magnitude. 相似文献
5.
Sunay V. Chankeshwara 《Tetrahedron letters》2006,47(7):1087-1091
Commercially available copper(II) tetrafluoroborate hydrate was found to be a highly efficient catalyst for chemoselective N-tert-butoxycarbonylation of amines with di-tert-butyl dicarbonate under solvent-free conditions and at room temperature. Various aromatic amines were protected as their N-tert-butyl carbamates in high yields and in short times. No competitive side reactions such as isocyanate, urea, and N,N-di-t-Boc formation was observed. Chemoselective N-tert-butoxycarbonylation was achieved with substrates bearing OH and SH groups. Chiral α-amino acid esters afforded the corresponding N-t-Boc derivatives in excellent yields. 相似文献
6.
7.
Krishna Nand Singh 《合成通讯》2013,43(16):2651-2654
A safe and simple method of preparing organic carbamates has been achieved from amines and carbon dioxide using tetraethylammonium superoxide generated in situ. 相似文献
8.
Argyro G. Fragkaki Georgia Petropoulou Ioanna Athanasiadou Polyxeni Kiousi Nassia Kioukia‐Fougia Helen Archontaki Evangelos Bakeas Yiannis S. Angelis 《Journal of separation science》2020,43(11):2154-2161
Anabolic androgenic steroids are widely abused substances in sports doping. Their detection present limitations regarding the use of soft ion sources such as electrospray or atmospheric pressure chemical ionization by liquid chromatography–tandem mass spectrometry. In the current study, a novel derivatization method was developed for the ionization enhancement of selected anabolic androgenic steroids. The proposed method aims at the introduction of an easily ionizable moiety into the steroid molecule by converting the hydroxyl groups into imidazole carbamates using 1,1′‐carbonyldiimidazole as derivatization reagent. The proposed method was applied to water and urine samples spiked with exogenous anabolic androgenic steroids in various concentration levels. Steroid imidazole carbamate derivatives have shown intensive [M+H]+ signals under electrospray ionization and common fragmentation patterns in tandem mass spectrometry mode with [M‐CO2+H]+ and [M‐ΙmCO2+H]+ as major ions with low collision energy. The obtained results showed that the majority of steroids were detectable at concentrations equal or lower to their minimum required performance level according to the World Anti‐Doping Agency technical document. The proposed method is sensitive with a preparation procedure that could be easily applied to the analysis of doping control samples. 相似文献
9.
Jin Tanaka Yu Shibata Anton Joseph Juntaro Nogami Jyunichi Terasawa Ryo Yoshimura Prof. Dr. Ken Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(26):5774-5779
It has been established that a newly developed cyclopentadienyl rhodium(III) [CpARhIII] complex, bearing an acidic secondary amide moiety on the Cp ring, is able to catalyze the ortho-bromination of O-phenyl carbamates with N-bromosuccinimide (NBS) at room temperature. The presence of the acidic secondary amide moiety on the CpA ligand accelerates the bromination by the hydrogen bond between the acidic NH group of the CpA ligand and the carbonyl group of NBS. 相似文献
10.
Synthesis of 8‐Aminoquinolines by Using Carbamate Reagents: Facile Installation and Deprotection of Practical Amidating Groups 下载免费PDF全文
Hye Kyung Kim Prof. Dr. Seth R. Marder Prof. Dr. Sukbok Chang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(48):17200-17204
Described herein is the development of practical routes to 8‐aminoquinolines by using readily installable and easily deprotectable amidating reagents. Two scalable procedures were optimized under RhIII‐catalyzed conditions: i) the use of pre‐generated chlorocarbamates and ii) a two‐step one‐pot process that directly employs carbamates. Both approaches are highly convenient for the gram‐scale synthesis of 8‐aminoquinolines under mild conditions. Facile deprotection of the synthetically versatile amidating groups was achieved under the Pd‐catalyzed transfer hydrogenation conditions with simultaneous deoxygenation of quinoline N‐oxides, thus yielding 8‐aminoquinolines in excellent overall efficiency. 相似文献