462-08-8Relevant articles and documents
Preparation of new pyrido[3,4-b]thienopyrroles and pyrido[4,3-e]thienopyridazines
Stockmann, Vegar,Fiksdahl, Anne
, p. 7626 - 7632 (2008)
Two new types of pyrido-fused tris-heterocycles (1a,b and 2a,b) have been prepared from 3-aminopyridine in five/six steps. A synthetic strategy for the preparation of the novel pyrido[3,4-b]thieno[2,3- and 3,2-d]pyrroles (1a,b) and pyrido[4,3-e]thieno[2,3- and 3,2-c]pyridazines (2a,b) has been studied. The Suzuki cross coupling of the appropriate 2- and 3-thienoboronic acids (3,4) and 4-bromo-3-pyridylpivaloylamide (9) afforded the biaryl coupling products (10,11) in high yields (85%). Diazotization of the hydrolysed (2-thienyl)-coupling product (12) and azide substitution gave the 3-azido-4-(2-thienyl)pyridine intermediate (72%, 14). 3-Azido-4-(3-thienyl)pyridine (15) was prepared by exchanging the previous order of reactions. The desired β-carboline thiophene analogues (1a,b) were obtained via the nitrene by thermal decomposition of the azido precursors (14,15). By optimising conditions for intramolecular diazocoupling, the corresponding pyridazine products (72-83%, 2a,b) were afforded.
Robust ultrafine ruthenium nanoparticles enabled by covalent organic gel precursor for selective reduction of nitrobenzene in water
Zhong, Hong,Gong, Yaqiong,Liu, Wenhui,Zhang, Bingbing,Hu, Shuangqi,Wang, Ruihu
, p. 2345 - 2351 (2019)
Metal nanoparticles (NPs) supported on nitrogen-doped porous carbon (NPC) are one type of promising heterogeneous catalysts. The tuning and understanding of metal-support interactions are crucial for the design and synthesis of highly durable and efficient heterogeneous catalytic systems. Here, we present an effective strategy to integrate ultrafine metal NPs into NPC via utilizing a covalent organic gel (COG) as the precursor for the first time. The ruthenium (Ru) NPs were uniformly dispersed in NPCs with the average size as low as 1.90 ± 0.4 nm. Irrespective of their ultrafine size, Ru NPs showed unprecedented stability and recyclability in Ru-catalyzed reduction of nitrobenzene and were greatly superior to commercial Ru/C and NPC-supported Ru NPs synthesized by the traditional post-loading method. This synthetic strategy can be extended to the synthesis of other metal or alloy NPs for a variety of advanced applications.
Ligand compound for copper catalyzed aryl halide coupling reaction, catalytic system and coupling reaction
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Paragraph 0111-0118; 0120, (2021/05/29)
The invention provides a ligand compound capable of being used for copper catalyzed aryl halide coupling reaction, the ligand compound is a three-class compound containing a 2-(substituted or non-substituted) aminopyridine nitrogen-oxygen group, and the invention also provides a catalytic system for the aryl halide coupling reaction. Thecatalytic system comprises a copper catalyst, a compound containing a 2-(substituted or non-substituted) aminopyridine nitrogen-oxygen group adopted as a ligand, alkali and a solvent, and meanwhile, the invention also provides a system for the aryl halide coupling reaction adopting the catalyst system. The compound containing the 2-(substituted or non-substituted) aminopyridine nitrogen oxygen group can be used as the ligand for the copper catalyzed aryl chloride coupling reaction, and the ligand is stable under a strong alkaline condition and can well maintain catalytic activity when being used for the copper-catalyzed aryl chloride coupling reaction. In addition, the copper catalyst adopting the compound as the ligand can particularly effectively promote coupling of copper catalyzed aryl chloride and various nucleophilic reagents which are difficult to generate under conventional conditions, C-N, C-O and C-S bonds are generated, and numerous useful small molecule compounds are synthesized. Therefore, the aryl halide coupling reaction has a very good large-scale application prospect by adopting the copper catalysis system of the ligand.
Porous polymeric ligand promoted copper-catalyzed C-N coupling of (hetero)aryl chlorides under visible-light irradiation
Wang, Erfei,Chen, Kaixuan,Chen, Yinan,Zhang, Jiawei,Lin, Xinrong,Chen, Mao
, p. 17 - 21 (2020/11/04)
A porous polymeric ligand (PPL) has been synthesized and complexed with copper to generate a heterogeneous catalyst (Cu@PPL) that has facilitated the efficient C-N coupling with various (hetero)aryl chlorides under mild conditions of visible-light irradiation at 80 °C (58 examples, up to 99% yields). This method could be applied to both aqueous ammonia and substituted amines, and is compatible to a variety of functional groups and heterocycles, as well as allows tandem C-N couplings with conjunctive dihalides. Furthermore, the heterogeneous characteristic of Cu@PPL has enabled a straightforward catalyst separation in multiple times of recycling with negligible catalytic efficiency loss by simple filtration, affording reaction mixtures containing less than 1 ppm of Cu residue. [Figure not available: see fulltext.]
Magnetically‐recoverable Schiff base complex of Pd(II) immobilized on Fe3O4@SiO2 nanoparticles: an efficient catalyst for the reduction of aromatic nitro compounds to aniline derivatives
Azadi, Sedigheh,Esmaeilpour, Mohsen,Sardarian, Ali Reza
, p. 809 - 821 (2021/07/20)
Fe3O4@SiO2/Schiff base/Pd(II) is reported as a magnetically recoverable heterogeneous catalyst for the chemoselective reduction of aromatic nitro compounds to the corresponding amines through catalytic transfer hydrogenation (CTH). In this regard, a small amount of the nanocatalyst (0.52?mol% Pd) and hydrazine hydrate, showing safe characteristics and perfect ability as the hydrogen donor, were added to the nitro substrates. The experiments described the successful reduction of aromatic nitro compounds with good to excellent yields and short reaction times. The catalyst, due to its magnetic property, could be simply separated from the reaction mixture by a permanent magnet and reused in seven consecutive reactions without considerable loss in its activity. Moreover, the leaching of Pd was only 3.6% after the seventh run. Thus, the most striking feature of this method is to use a small amount of the magnetic nanocatalyst along with a cheap and safe hydrogen source to produce the important amine substances selectively, which makes the method economical, cheap, environmentally friendly, and simple. Graphic abstract: [Figure not available: see fulltext.]
