14432-12-3Relevant articles and documents
Indirect reduction of CO2and recycling of polymers by manganese-catalyzed transfer hydrogenation of amides, carbamates, urea derivatives, and polyurethanes
Liu, Xin,Werner, Thomas
, p. 10590 - 10597 (2021/08/20)
The reduction of polar bonds, in particular carbonyl groups, is of fundamental importance in organic chemistry and biology. Herein, we report a manganese pincer complex as a versatile catalyst for the transfer hydrogenation of amides, carbamates, urea derivatives, and even polyurethanes leading to the corresponding alcohols, amines, and methanol as products. Since these compound classes can be prepared using CO2as a C1 building block the reported reaction represents an approach to the indirect reduction of CO2. Notably, these are the first examples on the reduction of carbamates and urea derivatives as well as on the C-N bond cleavage in amides by transfer hydrogenation. The general applicability of this methodology is highlighted by the successful reduction of 12 urea derivatives, 26 carbamates and 11 amides. The corresponding amines, alcohols and methanol were obtained in good to excellent yields up to 97%. Furthermore, polyurethanes were successfully converted which represents a viable strategy towards a circular economy. Based on control experiments and the observed intermediates a feasible mechanism is proposed.
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.
Aluminum Metal-Organic Framework-Ligated Single-Site Nickel(II)-Hydride for Heterogeneous Chemoselective Catalysis
Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Dwivedi, Ashutosh,Manna, Kuntal
, p. 3943 - 3957 (2021/04/12)
The development of chemoselective and heterogeneous earth-abundant metal catalysts is essential for environmentally friendly chemical synthesis. We report a highly efficient, chemoselective, and reusable single-site nickel(II) hydride catalyst based on robust and porous aluminum metal-organic frameworks (MOFs) (DUT-5) for hydrogenation of nitro and nitrile compounds to the corresponding amines and hydrogenolysis of aryl ethers under mild conditions. The nickel-hydride catalyst was prepared by the metalation of aluminum hydroxide secondary building units (SBUs) of DUT-5 having the formula of Al(μ2-OH)(bpdc) (bpdc = 4,4′-biphenyldicarboxylate) with NiBr2 followed by a reaction with NaEt3BH. DUT-5-NiH has a broad substrate scope with excellent functional group tolerance in the hydrogenation of aromatic and aliphatic nitro and nitrile compounds under 1 bar H2 and could be recycled and reused at least 10 times. By changing the reaction conditions of the hydrogenation of nitriles, symmetric or unsymmetric secondary amines were also afforded selectively. The experimental and computational studies suggested reversible nitrile coordination to nickel followed by 1,2-insertion of coordinated nitrile into the nickel-hydride bond occurring in the turnover-limiting step. In addition, DUT-5-NiH is also an active catalyst for chemoselective hydrogenolysis of carbon-oxygen bonds in aryl ethers to afford hydrocarbons under atmospheric hydrogen in the absence of any base, which is important for the generation of fuels from biomass. This work highlights the potential of MOF-based single-site earth-abundant metal catalysts for practical and eco-friendly production of chemical feedstocks and biofuels.
Preparation method of 2-chloro-4-aminopyridine
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, (2020/05/05)
The invention belongs to the field of organic synthesis, and particularly relates to a preparation method of 2-chloro-4-aminopyridine. The preparation method comprises the following steps: (1) using 2-chloropyridine as a raw material and chloroform as a solvent, and generating 2-chloropyridine oxide under the action of m-chloroperoxybenzoic acid; (2) reacting 2-chloropyridine oxide with a mixed acid composed of concentrated nitric acid and concentrated sulfuric acid to generate 2-chloro-4-nitropyridine oxynitride; and (3) reducing 2-chloro-4-nitropyridine oxynitride into 2-chloro-4-aminopyridine. The method has the beneficial effects that the reaction conditions are mild, the operation is easy, the post-treatment is simple, the scale-up production is easy, the method is very suitable for industrial production; the catalytic effect is good, the yield is high; the raw materials are cheap, and the production cost is low.
A 2 - chloro -4 - aminopyridine preparation method
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, (2019/05/28)
The invention belongs to the field of organic synthesis, in particular relates to a 2 - chloro - 4 - aminopyridine preparation method, comprises the following steps: (1) to 2 - chloro pyridine as raw materials, chloroform as solvent, under the action of the meta-chloroperoxybenzoic acid to produce 2 - chloro pyridine oxide; (2) 2 - chloro pyridine oxide by the concentrated nitric acid in concentrated sulfuric acid the acid produced by the reaction of a 2 - chloro - 4 - nitro pyridine nitrogen oxides; (3) 2 - chloro - 4 - nitro pyridine nitrogen oxide reduction is 2 - chloro - 4 - aminopyridine. The beneficial effect of the invention is: mild reaction conditions, is easy to operate, after treatment is simple, and easy to enlarge production, is extremely suitable for industrial production; good catalytic effect, high yield; low prices of raw materials, the production cost is low.
Catalytic Reductions and Tandem Reactions of Nitro Compounds Using in Situ Prepared Nickel Boride Catalyst in Nanocellulose Solution
Prathap, Kaniraj Jeya,Wu, Qiong,Olsson, Richard T.,Dinér, Peter
supporting information, p. 4746 - 4749 (2017/09/23)
A mild and efficient method for the in situ reduction of a wide range of nitroarenes and aliphatic nitrocompounds to amines in excellent yields using nickel chloride/sodium borohydride in a solution of TEMPO-oxidized nanocellulose in water (0.01 wt %) is described. The nanocellulose has a stabilizing effect on the catalyst, which increases the turnover number and enables low loading of nickel catalyst (0.1-0.25 mol % NiCl2). In addition, two tandem protocols were developed in which the in situ formed amines were either Boc-protected to carbamates or further reacted with an epoxide to yield β-amino alcohols in excellent yields.
Design and synthesis of purine analogues as highly specific ligands for FcyB, a ubiquitous fungal nucleobase transporter
Lougiakis, Nikolaos,Gavriil, Efthymios-Spyridon,Kairis, Markelos,Sioupouli, Georgia,Lambrinidis, George,Benaki, Dimitra,Krypotou, Emilia,Mikros, Emmanuel,Marakos, Panagiotis,Pouli, Nicole,Diallinas, George
, p. 5941 - 5952 (2016/11/09)
In the course of our study on fungal purine transporters, a number of new 3-deazapurine analogues have been rationally designed, based on the interaction of purine substrates with the Aspergillus nidulans FcyB carrier, and synthesized following an effective synthetic procedure. Certain derivatives have been found to specifically inhibit FcyB-mediated [3H]-adenine uptake. Molecular simulations have been performed, suggesting that all active compounds interact with FcyB through the formation of hydrogen bonds with Asn163, while the insertion of hydrophobic fragments at position 9 and N6 of 3-deazaadenine enhanced the inhibition.
Effective Hydrogenation of Haloaromatic Nitro Compounds Catalysed by Iridium Nanoparticles Deposited on Multiwall Carbon Nanotubes
Li, Hua-Bin,Liu, Lu,Ma, Xiao-Yan
, p. 1499 - 1505 (2016/06/09)
Iridium nanoparticles immobilized on multiwall carbon nanotubes composites were synthesized using anhydrous iridium trichloride as a precursor. The as-prepared composites were applied as catalysts for the hydrogenation of haloaromatic nitro compounds at room temperature and balloon hydrogen pressure in a methanol/water mixture, showing a selectivity of 99.9% to p-chloroaniline at complete conversion of p-chloronitrobenzene. Moreover, the catalysts also exhibited excellent catalytic properties for the reactants with electron-accepting, electron-donating, and heterocycle groups. The high activity and selectivity of the catalyst was probably attributed to the interaction such as competitive adsorption and hydrogen bonding between solvent water and reactants.
First and efficient method for reduction of aliphatic and aromatic nitro compounds with zinc borohydride as pyridine zinc tetrahydroborato complex: A new stable ligand-metal borohydride
Zeynizadeh, Behzad,Zahmatkesh, Karam
, p. 267 - 271 (2007/10/03)
Pyridine zinc tetrahydroborate, [(Py)Zn(BH4)2], as a new stable ligand-metal borohydride, is prepared quantitatively by complexation of 1:1 zinc borohydride and pyridine at room temperature. This reagent efficiently reduces different aromatic and aliphatic nitro compounds to their primary amines in refluxing THF. In addition, the reduction shows chemoselectivity for aliphatic nitro compounds over the aromatic nitro compounds.
Synthesis of the analogue nucleoside 3-deaza-2'-deoxycytidine and its template activity with DNA polymerase
Searls, Tim,McLaughlin, Larry W.
, p. 11985 - 11996 (2007/10/03)
A new synthesis of the nucleoside analogue 3-deaza-2'-deoxycytidine is described. The N3-nitrogen of dC is involved in the central hydrogen bond of a dG-dC base pair. The relative importance of hydrogen bonding as a controlling factor in the activity of DNA polymerase is examined by studying both duplex stability and template effects for this dc3C nucleoside. Duplexes containing dG-dc3C base pairs were strongly destabilized while templates containing the analogue nucleoside were found to incorporate only the complementary dG triphosphate, similar to observations with templates containing the native 2'-deoxycytidine.
