611-34-7Relevant articles and documents
Continuous and Selective Hydrogenation of Heterocyclic Nitroaromatics in a Micropacked Bed Reactor
Chen, Xingkun,Duan, Xiaonan,Wang, Xuepeng,Zhang, Jisong
, p. 2100 - 2109 (2021/09/08)
The hydrogenation of heterocyclic nitroaromatics is of great importance in the pharmaceutical industry for the synthesis of key intermediates. However, high selectivity is difficult to achieve in conventional batch reactors owing to severe back mixing and poor mass transfer performance, resulting in the high requirement for subsequent separation processes. In this work, a continuous flow system based on a micropacked bed reactor is developed for the selective hydrogenation of heterocyclic nitroaromatics and the reductions of 5-nitroisoquinoline to 5-aminoisoquinoline and 5-amino-1,2,3,4-tetrahydroisoquinoline are selected as the model reactions. With the optimal reaction conditions, maximal yields of 99.9% (5-aminoisoquinoline) and 99.3% (5-amino-1,2,3,4-tetrahydroisoquinoline) are obtained successfully. Moreover, this system exhibits remarkable performance for the selective hydrogenation of relevant heterocyclic nitroaromatics with all yields beyond the level of 97.5%. The continuous flow system enables efficient hydrogenation of heterocyclic nitroaromatics and remarkable selectivity of target products with shorter reaction time and safer operation compared with batch reactors.
Cyclic (Alkyl)(amino)carbene Ligand-Promoted Nitro Deoxygenative Hydroboration with Chromium Catalysis: Scope, Mechanism, and Applications
Zhao, Lixing,Hu, Chenyang,Cong, Xuefeng,Deng, Gongda,Liu, Liu Leo,Luo, Meiming,Zeng, Xiaoming
supporting information, p. 1618 - 1629 (2021/01/25)
Transition metal catalysis that utilizes N-heterocyclic carbenes as noninnocent ligands in promoting transformations has not been well studied. We report here a cyclic (alkyl)(amino)carbene (CAAC) ligand-promoted nitro deoxygenative hydroboration with cost-effective chromium catalysis. Using 1 mol % of CAAC-Cr precatalyst, the addition of HBpin to nitro scaffolds leads to deoxygenation, allowing for the retention of various reducible functionalities and the compatibility of sensitive groups toward hydroboration, thereby providing a mild, chemoselective, and facile strategy to form anilines, as well as heteroaryl and aliphatic amine derivatives, with broad scope and particularly high turnover numbers (up to 1.8 × 106). Mechanistic studies, based on theoretical calculations, indicate that the CAAC ligand plays an important role in promoting polarity reversal of hydride of HBpin; it serves as an H-shuttle to facilitate deoxygenative hydroboration. The preparation of several commercially available pharmaceuticals by means of this strategy highlights its potential application in medicinal chemistry.
Method for preparing amine through catalytic reduction of nitro compound by cyclic (alkyl) (amino) carbene chromium complex
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Paragraph 0015, (2021/04/17)
The cyclic (alkyl) (amino) carbene chromium complex is prepared from corresponding ligand salt, alkali and CrCl3 and used for catalyzing pinacol borane to reduce nitro compounds in an ether solvent under mild conditions to generate corresponding amine. The method for preparing amine has the advantages of cheap and accessible raw materials, mild reaction conditions, wide substrate application range, high selectivity and the like, and is simple to operate.
Palladium supported on metal–organic framework as a catalyst for the hydrogenation of nitroarenes under mild conditions
Bao, Lingxiang,Fei, Teng,Li, Jiazhe,Pang, Siping,Sun, Chenghui,Yan, Zhiyuan,Yu, Zongbao
, (2020/03/24)
Sustainable development demands an environmentally friendly and efficient method for the hydrogenation of organic molecules, including the hydrogenation of functionalized nitroarenes. In this study, a highly active and selective metal–organic framework-supported palladium catalyst was prepared for the catalytic hydrogenation of nitroarenes. High selectivity (>99%) and excellent yield (98%) of aniline were realized after 2 hours in ethanol under hydrogen (1 atm) at room temperature. The reductions were successfully carried out in the presence of a wide range of other reducible functional groups. More importantly, the catalyst was very stable without the loss of its catalytic activity after five cycles.
Method for reducing aromatic nitro into arylamine
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Paragraph 0189-0192; 0241-0244; 0281-0284, (2020/07/15)
The invention relates to a method for reducing aromatic nitro to arylamine. The method comprises the following steps: (1) taking an aromatic nitro compound as a raw material, water as a hydrogen source, a palladium compound, cheap and easy to obtain, as a catalyst and tetrahydroxydiboron as an additive to reduce nitro to obtain a product; (2) taking the aromatic nitro compound as the raw material, a copper salt, cheap and easy to obtain, as the catalyst, the tetrahydroxydiboron as the additive to reduce the nitro to obtain a product; and (3) taking the aromatic nitro compound as the raw material, water as the hydrogen source, and the tetrahydroxydiboron as the additive, without needing a metal catalyst, to reduce the nitro to obtain a product. A preparation method for the arylamine, which is provided by the invention, is mild in reaction condition, low in costs, environment-friendly, high in yield, and suitable for industrial production.
Visible-Light-Photocatalyzed Reductions of N-Heterocyclic Nitroaryls to Anilines Utilizing Ascorbic Acid Reductant
Todorov, Aleksandar R.,Aikonen, Santeri,Muuronen, Mikko,Helaja, Juho
supporting information, p. 3764 - 3768 (2019/05/24)
A photoreductive protocol utilizing [Ru(bpy)3]2+ photocatalyst, blue light LEDs, and ascorbic acid (AscH2) has been developed to reduce nitro N-heteroaryls to the corresponding anilines. Based on experimental and computational results and previous studies, we propose that the reaction proceeds via proton-coupled electron transfer between AscH2, photocatalyst, and the nitro N-heteroaryl. The method offers a green catalytic procedure to reduce, e.g., 4-/8-nitroquinolines to the corresponding aminoquinolines, substructures present in important antimalarial drugs.
Copper(ii)-catalyzed c-n coupling of aryl halides and n-nucleophiles promoted by quebrachitol or diethylene glycol
Chen, Guoliang,Chen, Yuanguang,Du, Fangyu,Fu, Yang,Wu, Ying,Zhou, Qifan
supporting information, p. 2161 - 2168 (2019/11/25)
Herein, we report the natural ligand quebrachitol (QCT) as a promoter for a Cu(II) catalyst, which is highly effective for N-Arylation of various amines and related aryl halides. A series of diarylamine derivatives were obtained in high yields by using diethylene glycol (DEG) as both ligand and solvent. The C-N coupling reactions proceed under mild conditions and exhibit good functional group tolerance.
Divergent Late-Stage (Hetero)aryl C?H Amination by the Pyridinium Radical Cation
Ham, Won Seok,Hillenbrand, Julius,Jacq, Jér?me,Genicot, Christophe,Ritter, Tobias
supporting information, p. 532 - 536 (2019/01/04)
(Hetero)arylamines constitute some of the most prevalent functional molecules, especially as pharmaceuticals. However, structurally complex aromatics currently cannot be converted into arylamines, so instead, each product isomer must be assembled through a multistep synthesis from simpler building blocks. Herein, we describe a late-stage aryl C?H amination reaction for the synthesis of complex primary arylamines that other reactions cannot access directly. We show and rationalize through a mechanistic analysis the reasons for the wide substrate scope and the constitutional diversity of the reaction, which gives access to molecules that would not have been readily available otherwise.
Mechanochemical catalytic transfer hydrogenation of aromatic nitro derivatives
Portada, Tomislav,Margeti?, Davor,?trukil, Vjekoslav
supporting information, (2018/12/11)
Mechanochemical ball milling catalytic transfer hydrogenation (CTH) of aromatic nitro compounds using readily available and cheap ammonium formate as the hydrogen source is demonstrated as a simple, facile and clean approach for the synthesis of substituted anilines and selected pharmaceutically relevant compounds. The scope of mechanochemical CTH is broad, as the reduction conditions tolerate various functionalities, for example nitro, amino, hydroxy, carbonyl, amide, urea, amino acid and heterocyclic. The presented methodology was also successfully integrated with other types of chemical reactions previously carried out mechanochemically, such as amide bond formation by coupling amines with acyl chlorides or anhydrides and click-type coupling reactions between amines and iso(thio)cyanates. In this way, we showed that active pharmaceutical ingredients Procainamide and Paracetamol could be synthesized from the respective nitro-precursors on milligram and gram scale in excellent isolated yields.
Cu-catalyzed reduction of azaarenes and nitroaromatics with diboronic acid as reductant
Pi, Danwei,Zhou, Haifeng,Zhou, Yanmei,Liu, Qixing,He, Renke,Shen, Guanshuo,Uozumi, Yasuhiro
, p. 2121 - 2129 (2018/03/23)
A ligand-free copper-catalyzed reduction of azaarenes with diboronic acid as reductant in an aprotic solvent under mild conditions has been developed. Most interestingly, the nitroazaarenes could be reduced exclusively to give the corresponding amines without touching the azaarene moieties. Furthermore, the reductive amination of aromatic nitro compounds and aromatic aldehydes has also been realized. A series of hydrogenated azaarenes and secondary amines were obtained with good functional group tolerance.
