20913-18-2Relevant articles and documents
A spectroscopic study of the model urethanes
Wang, Qiong,Stidham, Howard D.,Papadimitrakopolos, F.
, p. 421 - 434 (1994)
The synthesis, far infrared spectra, temperature-dependent mid-infrared spectra in the carbonyl and NH streching regions and the Fourier transform Raman spectra are reported for polycrystalline samples of three small diurethanes, 1,3-phenyl di(carbamic acid methyl ester), 2,6-toluene di(carbamic acid methyl ester) and 2,4-toluene di(carbamic acid methyl ester).An ab initio geometry optimization is reported for methyl N-phenyl carbamate using STO-3G and 3-21G basis sets, and for the three small diurethanes by molecular machanics methods using the Dreiding I force field.The results suggest that, in isotropic surroundings, only a very small number of the 256 posible conformers of the urethane groups in the three small diurethanes contribute appreciably to the structure.
Biotransformation of isofraxetin-6-O-β-D-glucopyranoside by Angelica sinensis (Oliv.) Diels callus
Zhou, Di,Zhang, Yuhua,Jiang, Zhe,Hou, Yue,Jiao, Kun,Yan, Chunyan,Li, Ning
, p. 248 - 253 (2016/12/27)
Isofraxetin-6-O-β-D-glucopyranoside, identified from traditional medicinal herbal Xanthoceras sorbifolia Bunge, has been demonstrated to be a natural neuroinflammatory inhibitor. In order to obtain more derivatives with potential anti-neuroinflammatory effects, biotransformation was carried out. According to the characteristics of coumarin skeleton, suspension cultures of Angelica sinensis (Oliv.) Diels callus (A. sinensis callus) were employed because of the presence of diverse phenylpropanoids biosynthetic enzymes. As a result, 15 products were yielded from the suspension cultures, including a new coumarin: 8′-dehydroxymethyl cleomiscosin A (1), together with 14 known compounds. Their structures were elucidated by extensive spectroscopic analysis. Furthermore, the biotransformed pathways were discussed. Among them, compound 13 was transformed from isofraxetin-6-O-β-D-glucopyranoside, while compounds 1–6, 10–12, 14–15 were derived from the culture medium stimulated by the substrate. The biotransformation processes include hydroxylation, oxidation and esterification. Furthermore, their inhibitory effects on lipopolysaccharide (LPS)-activated nitric oxide (NO) production were evaluated in BV2 microglial cells. It is worth noting that, 1, 1′-methanediylbis(4-methoxybenzene) (3), obtucarbamates A (5), 2-nonyl-4-hydroxyquinoline N-oxide (10) and 1H-indole-3-carbaldehyde (11) exhibited significant inhibitory effect against neuroinflammation with IC50values at 1.22, 10.57, 1.02 and 0.76?μM respectively, much stronger than that of the positive control minocycline (IC5035.82?μM).
Carbonylation of dinitrotoluene to dimethyl toluenedicarbamate; high efficiency of phosphorus acids as promoters for the palladium-phenanthroline catalytic system
Gasperini, Michela,Ragaini, Fabio,Cazzaniga, Chiara,Cenini, Sergio
, p. 105 - 120 (2007/10/03)
Phosphorus acids are excellent promoters for the palladium-phenanthroline catalyzed carbonylation of 2,4-dinitrotoluene to 2,4-toluenedicarbamate. For the first time, all intermediate nitrocarbamates and aminocarbamates have been independently synthesized and their amount after every catalytic reaction precisely quantified. An extensive optimization of all experimental variables has been carried out. The best acids are phenylphosphonic and 4-tolylphosphonic acids. The addition of 2,2-dimethoxypropane as an internal drying agent is highly beneficial. The addition of an amine derived from the starting dinitroarene increases both rate and selectivity of the carbonylation reaction. The complexes [Pd(Phen)2] [SbF6] and [Pd(Phen) 2][BArF4] [ArF = 3,5-(CF 3)2C6H3] have been prepared for the first time. The latter displays a markedly higher solubility than all other [Pd(Phen)2]2+ complexes. The effect of several possible promoters has also been investigated. Under the optimized experimental conditions, a 77.6% selectivity in dicarbamate was obtained when working at a molar ratio dinitrotoluene/Pd = 2920. At the end of the reaction, the dicarbamate spontaneously precipitates out of the solution in high yields upon cooling, with no inclusion of the acid promoter or of phenanthroline. 2,6-Dinitrotoluene can also be efficiently carbonylated to the corresponding dicarbamate.
