2587-02-2Relevant academic research and scientific papers
Highly selective hydrogenation of halogenated nitroarenes over Ru/CN nanocomposites by: In situ pyrolysis
Yue, Shengnan,Wang, Xueguang,Li, Shaoting,Sheng, Yao,Zou, Xiujing,Lu, Xionggang,Zhang, Chunlei
, p. 11861 - 11869 (2020/07/28)
A highly chemoselective and recyclable ruthenium catalyst for the hydrogenation of halogenated nitroarenes has been prepared via the simple in situ calcination of a mixture of melamine, glucose and ruthenium trichloride. Superfine Ru particles (2.3 ± 0.3 nm) were obtained and highly dispersed in the nitrogen-doped carbon matrix. The Ru/CN catalyst smoothly transforms a variety of halogenated nitroarenes to the corresponding haloanilines with high intrinsic activity (e.g. TOF = 1333 h-1 for p-chloronitrobenzene) and selectivity of more than 99.6percent. Furthermore, through an analysis of the products in the reaction process, it was concluded that there are two parallel reaction pathways (a direct pathway and an indirect pathway) for the hydrogenation of aromatic nitro compounds over the Ru/CN catalyst, and the direct pathway was proved to be dominant in catalyzing the intermediates. This journal is
Preparation method of 4-amino-2,6-dichloropyridine
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, (2021/03/21)
The invention relates to a preparation method of a halogen-substituted pyridylamine compound, particularly to a preparation method of 4-amino-2,6-dichloropyridine, wherein 2,6-dihydroxy isonicotinic acid is used as a raw material and is subjected to chlorination reaction, Curtius rearrangement or further amine protection group removal to obtain the product. The method has the advantages of accessible raw materials, high yield and low impurity content, avoids the use of explosive reagent sodium azide, and can be further applied to industrial production.
High Performance and Active Sites of a Ceria-Supported Palladium Catalyst for Solvent-Free Chemoselective Hydrogenation of Nitroarenes
Shi, Xiuxiu,Wang, Xueguang,Shang, Xingfu,Zou, Xiujing,Ding, Weizhong,Lu, Xionggang
, p. 3743 - 3751 (2017/10/16)
Cerium oxide-supported palladium catalysts (Pd/CeO2) prepared by a simple impregnation method exhibit exciting catalytic activity and high chemoselectivity for the solvent-free hydrogenation of a variety of substituted nitroarenes including the reducible functional groups to the corresponding aromatic amines under mild reaction conditions. Taking nitrobenzene as an example, the Pd/CeO2 catalyst can afford aniline yields of >99 % with turnover frequencies as high as 11 411 h?1 and 69 824 h?1 at 40 °C and 100 °C, respectively. Pd2+ ion species exist as isolated single atoms with ?Pd2+?O2??Ce4+? linkages on the surface of PdxCe1?xO2?σ solid solution and are found to be active sites for the selective hydrogenation of nitroarenes in the absence of solvent. The superior catalytic performance can be attributed to the cooperative effect between Pd2+ ions and unique surface sites of CeO2. A possible mechanism is proposed for the hydrogenation of nitroarenes with H2 over the Pd/CeO2. The Pd/CeO2 catalyst can be recovered easily and reused for at least seven recycling reactions without loss of catalytic properties.
Rapid heteroatom transfer to arylmetals utilizing multifunctional reagent scaffolds
Gao, Hongyin,Zhou, Zhe,Kwon, Doo-Hyun,Coombs, James,Jones, Steven,Behnke, Nicole Erin,Ess, Daniel H.,Kürti, László
, p. 681 - 688 (2017/06/30)
Arylmetals are highly valuable carbon nucleophiles that are readily and inexpensively prepared from aryl halides or arenes and widely used on both laboratory and industrial scales to react directly with a wide range of electrophiles. Although C-C bond formation has been a staple of organic synthesis, the direct transfer of primary amino (-NH2) and hydroxyl (-OH) groups to arylmetals in a scalable and environmentally friendly fashion remains a formidable synthetic challenge because of the absence of suitable heteroatom-transfer reagents. Here, we demonstrate the use of bench-stable N-H and N-alkyl oxaziridines derived from readily available terpenoid scaffolds as efficient multifunctional reagents for the direct primary amination and hydroxylation of structurally diverse aryl- and heteroarylmetals. This practical and scalable method provides one-step synthetic access to primary anilines and phenols at low temperature and avoids the use of transition-metal catalysts, ligands and additives, nitrogen-protecting groups, excess reagents and harsh workup conditions.
Solvent-Free Selective Hydrogenation of Nitroarenes Using Nanoclusters of Palladium Supported on Nitrogen-Doped Ordered Mesoporous Carbon
Huang, Haigen,Wang, Xueguang,Tan, Mingwu,Chen, Chenju,Zou, Xiujing,Ding, Weizhong,Lu, Xionggang
, p. 1485 - 1489 (2016/05/02)
The selective hydrogenation of nitroarenes is a key transformation for the production of aromatic amines, which are primary intermediates in the synthesis of pharmaceuticals, agrochemicals, and dyes. However, most reaction processes require toxic organic solvents and suffer from poor selectivity in the presence of other reducible groups. Herein, we report a successful example of nanoclusters of ultrafine Pd supported on N-modified ordered mesoporous CMK-3 carbon (Pd/N-CMK-3) prepared by a facile two-step impregnation route with aqueous solutions of 1,10-phenanthroline and H2PdCl4 that hydrogenated various nitroarenes highly efficiently and selectively to the corresponding aromatic amines with hydrogen in the absence of solvent. The Pd/N-CMK-3 catalyst could be recovered easily for multiple recycling reactions without a loss of catalytic performance.
Efficient synthesis of 4-amino-2,6-dichloropyridine and its derivatives
Ma, Congming,Liu, Zuliang,Yao, Qizheng
, p. 251 - 254 (2016/10/24)
A facile synthetic route to an important intermediate 4-amino-2,6-dichloropyridine was developed. Oxidation of 2,6-dichloropyridine as a starting material gave pyridine N-oxide derivative which was subjected to nitration followed by reduction. Subsequent nitration of the product and nucleophilic displacement reaction were carried out to afford fully substituted energetic pyridine derivatives. Most of the synthetic reactions proceeded under mild conditions.
Optimization of Triazine Nitriles as Rhodesain Inhibitors: Structure-Activity Relationships, Bioisosteric Imidazopyridine Nitriles, and X-ray Crystal Structure Analysis with Human CathepsinL
Ehmke, Veronika,Winkler, Edwin,Banner, David W.,Haap, Wolfgang,Schweizer, W. Bernd,Rottmann, Matthias,Kaiser, Marcel,Freymond, Celine,Schirmeister, Tanja,Diederich, Francois
, p. 967 - 975 (2013/07/27)
The cysteine protease rhodesain of Trypanosoma brucei parasites causing African sleeping sickness has emerged as a target for the development of new drug candidates. Based on a triazine nitrile moiety as electrophilic headgroup, optimization studies on the substituents for the S1, S2, and S3 pockets of the enzyme were performed using structure-based design and resulted in inhibitors with inhibition constants in the single-digit nanomolar range. Comprehensive structure-activity relationships clarified the binding preferences of the individual pockets of the active site. The S1 pocket tolerates various substituents with a preference for flexible and basic side chains. Variation of the S2 substituent led to high-affinity ligands with inhibition constants down to 2nM for compounds bearing cyclohexyl substituents. Systematic investigations on the S3 pocket revealed its potential to achieve high activities with aromatic vectors that undergo stacking interactions with the planar peptide backbone forming part of the pocket. X-ray crystal structure analysis with the structurally related enzyme human cathepsinL confirmed the binding mode of the triazine ligand series as proposed by molecular modeling. Sub-micromolar inhibition of the proliferation of cultured parasites was achieved for ligands decorated with the best substituents identified through the optimization cycles. In cell-based assays, the introduction of a basic side chain on the inhibitors resulted in a 35-fold increase in antitrypanosomal activity. Finally, bioisosteric imidazopyridine nitriles were studied in order to prevent off-target effects with unselective nucleophiles by decreasing the inherent electrophilicity of the triazine nitrile headgroup. Using this ligand, the stabilization by intramolecular hydrogen bonding of the thioimidate intermediate, formed upon attack of the catalytic cysteine residue, compensates for the lower reactivity of the headgroup. The imidazopyridine nitrile ligand showed excellent stability toward the thiol nucleophile glutathione in a quantitative invitro assay and fourfold lower cytotoxicity than the parent triazine nitrile.
FUSED PYRIDINE DERIVATIVES
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Page/Page column 51-52, (2012/12/13)
Fused pyridine derivatives shown as the general formula (I), and their pharmaceutically acceptable salts, stereoisomers or solvates thereof are disclosed, which belong to the technical field of medicines. The R1, R2, R3, Q, X and Y substituents in formula (I) are defined as in the description. Also disclosed are the preparation methods, pharmaceutical compositions comprising the compounds and uses of the compounds in the manufacture of the medicine for the treatment and/or prevention of noninsulin-dependent diabetes, hyperglycemia, hyperlipidemia and insulin resistance.
FUSED PYRIDINE DERIVATIVES
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Page/Page column 58-59, (2012/12/13)
Fused pyridine derivatives shown as the general formula (I), and their pharmaceutically acceptable salts, stereoisomers or solvates thereof are disclosed, which belong to the technical field of medicines. The R1, R2, R3, Q, X and Y substituents in formula (I) are defined as in the description. Also disclosed are the preparation methods, pharmaceutical compositions comprising the compounds and uses of the compounds in the manufacture of the medicine for the treatment and/or prevention of noninsulin-dependent diabetes, hyperglycemia, hyperlipidemia and insulin resistance.
5-Substituted 1H-pyrrolo[3,2-b]pyridines as inhibitors of gastric acid secretion
Palmer, Andreas Marc,Muench, Gabriela,Brehm, Christof,Zimmermann, Peter Jan,Buhr, Wilm,Feth, Martin Philipp,Simon, Wolfgang Alexander
, p. 1511 - 1530 (2008/09/18)
A series of novel 1H-pyrrolo[3,2-b]pyridines was prepared relying on a copper iodide catalyzed cyclization of 2-prop-1-ynylpyridin-3-amines. A structure-activity relationship was established focusing on the influence of the substitution pattern in position 1, 3, and 5 of the heterocycle on anti-secretory activity, lipophilicity, and pKa value. Some of the compounds proved to be potent inhibitors of the gastric acid pump.
