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A novel approach towards chemoselective reduction of nitro to amine
Chemo selective reduction of a wide range of aromatic nitro compound has been performed by using inexpensive Zn powder and CuSO4 system in water medium at room temperature. This system has high tolerance to other highly reducible groups present in nitro substance along with high conversation and selectivity. This chemo-selective reduction also provides a facile root for the synthesis of other industrially important fine chemicals or biologically important compounds where other highly reducible groups are present in close proximity to the targeted nitro groups.
Dasgupta, Hridoydip Ranjan,Mukherjee, Suvodip,Ghosh, Pranab
(2019)
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Adams,Pachter
p. 4906
(1952)
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One-Pot Fabrication of Pd Nanoparticles?Covalent-Organic-Framework-Derived Hollow Polyamine Spheres as a Synergistic Catalyst for Tandem Catalysis
Facile fabrication of nanocatalysts consisting of metal nanoparticles (NPs) anchored on a functional support is highly desirable, yet remains challenging. Covalent organic frameworks (COFs) provide an emerging materials platform for structural control and functional design. Here, a facile one-pot in situ reduction approach is demonstrated for the encapsulation of small Pd NPs into the shell of COF-derived hollow polyamine spheres (Pd?H-PPA). In the one-pot synthetic process, the nucleation and growth of Pd NPs in the cavities of the porous shell take place simultaneously with the reduction of imine linkages to secondary amine groups. Pd?H-PPA shows a significantly enhanced catalytic activity and recyclability in the tandem dehydrogenation of ammonia borane and selective hydrogenation of nitroarenes through an adsorption–activation–reaction mechanism. The strong interactions of the secondary amine linkage with borane and nitroarene molecules afford a positive synergy to promote the catalytic reaction. Moreover, the hierarchical structure of Pd?H-PPA allows the accessibility of active Pd NPs to reactants.
Yang, Xinyi,He, Yajun,Li, Liuyi,Shen, Jinni,Huang, Jianhui,Li, Lingyun,Zhuang, Zanyong,Bi, Jinhong,Yu, Yan
p. 1864 - 1870
(2020)
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N,N-Chelate nickel(II) complexes bearing Schiff base ligands as efficient hydrogenation catalysts for amine synthesis
Five N, N-chelate nickel (II) complexes bearing N-(2-pyridinylmethylene)-benzylamine ligands with different substituent groups were synthesized in good yields. The nickel complexes exhibited prominent catalytic efficiency toward amine synthesis from nitro compounds by using NaBH4 or H2 as hydrogen source through two catalytic systems. Various amines with different substituents were obtained in moderate to excellent yields. All substrates with electron-donating and electron-withdrawing properties were tolerated in the two reduction systems. Given the efficient catalytic activity, broad substance scope, and mild reduction conditions, the nickel catalysts have potential applications in industrial production.
Xu, Mengyin,Wang, Yang,Zhou, Yifeng,Yao, Zi-Jian
(2021/12/09)

Dual Reactivity of 1,2,3,4-Tetrazole: Manganese-Catalyzed Click Reaction and Denitrogenative Annulation
A general catalytic method using a Mn-porphyrin-based catalytic system is reported that enables two different reactions (click reaction and denitrogenative annulation) and affords two different classes of nitrogen heterocycles, 1,5-disubstituted 1,2,3-triazoles (with a pyridyl motif) and 1,2,4-triazolo-pyridines. Mechanistic investigations suggest that although the click reaction likely proceeds through an ionic mechanism, which is different from the traditional click reaction, the denitrogenative annulation reaction likely proceeds via an electrophilic metallonitrene intermediate rather than a metalloradical intermediate. Collectively, this method is highly efficient and offers several advantages over other methods. For example, this method excludes a multi-step synthesis of the N-heterocyclic molecules described and produces only environmentally benign N2 gas a by-product.
Chattopadhyay, Buddhadeb,Das, Sandip Kumar,Khatua, Hillol,Roy, Satyajit
p. 304 - 312
(2020/10/29)

Indirect reduction of CO2and recycling of polymers by manganese-catalyzed transfer hydrogenation of amides, carbamates, urea derivatives, and polyurethanes
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.
Liu, Xin,Werner, Thomas
p. 10590 - 10597
(2021/08/20)

Development and Application of Efficient Ag-based Hydrogenation Catalysts Prepared from Rice Husk Waste
The development of strategies for the sustainable management and valorization of agricultural waste is of outmost importance. With this in mind, we report the use of rice husk (RH) as feedstock for the preparation of heterogeneous catalysts for hydrogenation reactions. The catalysts were prepared by impregnating the milled RH with a silver nitrate solution followed by carbothermal reduction. The composition and morphology of the prepared catalysts were fully assessed by IR, AAS, ICP-MS, XPS, XRD and STEM techniques. This novel bio-genic silver-based catalysts showed excellent activity and remarkable selectivity in the hydrogenation of nitro groups in both aromatic and aliphatic substrates, even in the presence of reactive functionalities like halogens, carbonyls, borate esters or nitriles. Recycling experiments showed that the catalysts can be easily recovered and reused multiple times without significant drop in performance and without requiring re-activation.
Unglaube, Felix,Kreyenschulte, Carsten Robert,Mejía, Esteban
p. 2583 - 2591
(2021/04/09)

Cyclic (Alkyl)(amino)carbene Ligand-Promoted Nitro Deoxygenative Hydroboration with Chromium Catalysis: Scope, Mechanism, and Applications
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.
Zhao, Lixing,Hu, Chenyang,Cong, Xuefeng,Deng, Gongda,Liu, Liu Leo,Luo, Meiming,Zeng, Xiaoming
supporting information
p. 1618 - 1629
(2021/01/25)

Efficient reduction of nitro compounds and domino preparation of 1-substituted-1H-1,2,3,4-tetrazoles by Pd(ii)-polysalophen coated magnetite NPs as a robust versatile nanocomposite
A new, versatile, and green methodology has been developed for the efficient NaBH4-reduction of nitroarenes as well as the domino/reduction MCR preparation of 1-substituted-1H-1,2,3,4-tetrazoles using Pd(ii)-polysalophen coated magnetite NPs as an efficient heterogeneous magnetically recyclable nanocatalyst. Polysalophen was firstly prepared based on a triazine framework with a high degree of polymerization, then coordinated to Pd ions and, finally, the resulting hybrid was immobilized on magnetite NPs. The catalyst was characterized by various instrumental and analytical methods, including GPC, DLS, N2adsorption-desorption, TGA, VSM, TEM, HRTEM, EDX, XPS, XRD, and ICP analyses. The catalyst possesses dual-functionality including the reduction of nitroarenes and the construction of tetrazole rings all in one stepviaa domino protocol. High to excellent yields were obtained for both nitro reduction and the direct preparation of 1-substituted-1H-1,2,3,4-tetrazoles from nitro compounds. Insight into the mechanism was conducted by XPSin situas well as DLSin situalong with several control experiments. Recyclability of the catalyst was studied for 6 consecutive runs along with metal leaching measurements in each cycle.
Xu, DaPeng,Xiong, Meilu,Kazemnejadi, Milad
p. 12484 - 12499
(2021/04/14)

Biorenewable carbon-supported Ru catalyst for: N -alkylation of amines with alcohols and selective hydrogenation of nitroarenes
Herein, we developed a renewable carbon-supported Ru catalyst (Ru/PNC-700), which was facilely prepared via simple impregnation followed by the pyrolysis process. The prepared Ru/PNC-700 catalyst demonstrated remarkable catalytic activity in terms of conversion and selectivity towards N-alkylation of anilines with benzyl alcohol and chemoselective hydrogenation of aromatic nitro compounds. In addition, local anesthetic pharmaceutical agents (e.g., butamben and benzocaine), including key drug intermediates, were synthesized in excellent yields under mild conditions and in the presence of water as a green solvent. Moreover, the prepared Ru/PNC-700 catalyst could be easily recovered and reused up to five times without any apparent loss in activity and selectivity.
Goyal, Vishakha,Narani, Anand,Natte, Kishore,Poddar, Mukesh Kumar,Ray, Anjan,Sarki, Naina,Tripathi, Deependra
p. 14687 - 14694
(2021/08/23)

Development of sustainable and efficient nanocatalyst based on polyoxometalate/nickel oxide nanocomposite: A simple and recyclable catalyst for reduction of nitroaromatic compounds
In this paper, we report the synthesis and characterization of NiO@PolyMo nanocomposite. The newly synthesized nanocomposite was characterized by transmission electronmicroscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and powder X-ray diffraction (XRD). The particle sizes of the NiO@PolyMo nanocatalyst are in the range of 10–20 nm. Powder XRD patterns show that the phase of NiO@PolyMo remains unaltered even after the functionalization of NiO. The lattice fringes of d = 0.20 nm were observed, which correspond to the (111) plane of NiO phase. The newly synthesized material shows excellent catalytic performance and good selectivity for reduction of nitroarenes. The advantages of the present protocols are mild, and can be carried out using water as a solvent, which is an eco-friendly benign.
Kurbah, Sunshine Dominic
p. 1487 - 1495
(2021/04/22)

Oxidation/ MCR domino protocol for direct transformation of methyl benzene, alcohol, and nitro compounds to the corresponding tetrazole using a three-functional redox catalytic system bearing TEMPO/Co(III)-porphyrin/ Ni(II) complex
A redox catalytic system for oxidation-reduction reactions and the domino preparation of tetrazole compounds from nitro and alcohol precursors was designed, prepared and characterized by UV–vis, GPC, TGA, XRD, EDX, XPS, VSM, FE-SEM, TEM, DLS, BET, NMR, and ICP analyses. The catalyst was prepared via several successive steps by demetalation of chlorophyll b, copolymerization with acrylated TEMPO monomers, complexation with Ni and Co metals (In two different steps), then immobilized on magnetic nanoparticles. The presence of three functional groups including TEMPO, coordinated cobalt, and coordinated nickel in the catalyst, allowed the oxidation of various types of alcohols, alkyl benzenes as well as the reduction of nitro compounds by a single catalyst. All reactions yielded up to 97 % selectivity for oxidation and reduction reactions. Next, the ability of the catalyst to successfully convert alcohol, methyl benzenes and nitro to their corresponding tetrazoles was studied.
Mahmoudi, Boshra,Rostami, Amin,Kazemnejadi, Milad,Hamah-Ameen, Baram Ahmed
(2020/12/21)

Minimization of Back-Electron Transfer Enables the Elusive sp3 C?H Functionalization of Secondary Anilines
Anilines are some of the most used class of substrates for application in photoinduced electron transfer. N,N-Dialkyl-derivatives enable radical generation α to the N-atom by oxidation followed by deprotonation. This approach is however elusive to monosubstituted anilines owing to fast back-electron transfer (BET). Here we demonstrate that BET can be minimised by using photoredox catalysis in the presence of an exogenous alkylamine. This approach synergistically aids aniline SET oxidation and then accelerates the following deprotonation. In this way, the generation of α-anilinoalkyl radicals is now possible and these species can be used in a general sense to achieve divergent sp3 C?H functionalization.
Zhao, Huaibo,Leonori, Daniele
supporting information
p. 7669 - 7674
(2021/03/08)

Copper and L-(?)-quebrachitol catalyzed hydroxylation and amination of aryl halides under air
L-(?)-Quebrachitol, a natural product obtained from waste water of the rubber industry, was utilized as an efficient ligand for the copper-catalyzed hydroxylation and amination of aryl halides to selectively give phenols and aryl amines in water or 95percent ethanol. In addition, the hydroxylation of 2-chloro-4-hydroxybenzoic acid was validated on a 100-g scale under air.
Bao, Xuefei,Chen, Guoliang,Dong, Jinhua,Du, Fangyu,Li, Hui,Liang, Xinjie,Wu, Ying,Zhang, Yongsheng
supporting information

(2020/08/03)

CuIBiOI is an efficient novel catalyst in Ullmann-type CN– couplings with wide scope—A rare non-photocatalyic application
Preparation of a new, mixed-cationic layered CuIBiOI was prepared and its non-photocatalytic catalytic properties were explored. This solid substance had BiOI-like, lamellar and deflected structure resulting from CuI ion incorporation in the Bi2O2 layers. The as-prepared substance was fully characterized by XRD, Raman, far IR, UV–DR, XP spectroscopies, thermal (TG-DTG) and analytical (ICP-MS, SEM-EDX) methods, electron microscopies (SEM, TEM) as well as BET surface area measurements. By performing Ullmann-type CN– coupling reactions between aryl halides and aqueous ammonia, its catalytic capabilities were tested. The effects of solvents, added base and catalyst loading as well as reaction time and reaction temperature were scrutinized, and a green way for the reaction was identified. The recyclability of the catalyst without the loss of activity and its general applicability for a wide range of aryl halides were also demonstrated.
Djerdj, Igor,Kónya, Zoltán,Kocsis, Marianna,Kukovecz, ákos,Pálinkó, István,Sipos, Pál,Varga, Gábor
(2020/07/02)

A new ligand for copper-catalyzed amination of aryl halides to primary(hetero)aryl amines
N,N′-Bis(3,5-dimethoxyphenyl)cyclopentane-1,1-dicarboxamide was found as a new ligand for copper-catalyzed amination of aryl iodides, bromides and chlorides to afford various primary (hetero)aryl amines. These reactions proceeded efficiently under mild conditions when inexpensive aqueous ammonia (28% NH3 in H2O) was used as the amino source.
Chen, Dong,Dong, Xinrui,Jiang, Shang,Jiang, Sheng,Qiu, Yatao,Wu, Xiaoxing
supporting information

(2020/02/11)

Enhanced catalytic activity of natural hematite-supported ppm levels of Pd in nitroarenes reduction
In this work, Pd NPs supported on amine-modified natural hematite have been prepared and characterized. Using this simple catalyst, nitroaromatic compounds as a major cause of industrial pollution were reduced to corresponding amines with ppm levels of Pd in the presence of designer surfactant TPGS-750-M and NaBH4 at room temperature in aqueous media. Synergistic effect between hematite and Pd is responsible for the observed enhanced catalytic activity. This catalyst was recycled for at least four times with a small decrease in the activity.
Gholinejad, Mohammad,Shojafar, Mohammad,Sansano, José M.
p. 2033 - 2043
(2020/04/07)

Method for preparing amino compound by catalytically reducing nitro compound with alkaline earth metal hydride
The invention relates to a method for preparing an amino compound by catalytically reducing a nitro compound with alkaline earth metal hydride, and belongs to the technical field of organic synthesis.The method comprises the following steps: by taking a nitro compound as a reaction substrate, alkaline earth metal hydride as a hydrogen source and diborate as a catalyst, respectively adding the nitro compound, the alkaline earth metal hydride and the diborate into an organic solvent, stirring and heating to react for 3-20 hours at the reaction temperature of 50-150 DEG C; and after the reactionis finished, separating and purifying the reaction mother liquor to obtain the amino compound. The method has the advantages of simple synthesis steps, mild reaction conditions, avoiding of the use of high pressure hydrogen, no participation of transition metals in the reaction process, reduction of the reaction cost, greenness, environmental protection, and reduction of the environmental pollution.
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Paragraph 0060-0065

(2020/09/16)

Manganese-Catalyzed One-Pot Conversion of Nitroarenes into N-Methylarylamines Using Methanol
A manganese-catalyzed one-pot conversion of nitroarenes into N-methylarylamines has been developed. This transfer hydrogenation method employs a well-defined bench stable Mn PN3P pincer precatalyst in combination with methanol as both the reductant and the C1 source. A selection of commercially available nitroarenes was converted into N-methylarylamines in synthetically useful yields.
Mast, Nicolas,Morrill, Louis C.,Reed-Berendt, Benjamin G.
supporting information

(2020/03/03)

Superhydrophobic nickel/carbon core-shell nanocomposites for the hydrogen transfer reactions of nitrobenzene and N-heterocycles
In this work, catalytic hydrogen transfer as an effective, green, convenient and economical strategy is for the first time used to synthesize anilines and N-heterocyclic aromatic compounds from nitrobenzene and N-heterocycles in one step. Nevertheless, how to effectively reduce the possible effects of water on the catalyst by removal of the by-product water, and to further introduce water as the solvent based on green chemistry are still challenges. Since the structures and properties of carbon nanocomposites are easily modified by controllable construction, a one step pyrolysis process is used for controllable construction of micro/nano hierarchical carbon nanocomposites with core-shell structures and magnetic separation performance. Using various characterization methods and model reactions the relationship between the structure of Ni?NCFs (nickel-nitrogen-doped carbon frameworks) and catalytic performance was investigated, and the results show that there is a positive correlation between the catalytic performance and hydrophobicity of catalysts. Besides, the possible catalytically active sites, which are formed by the interaction of pyridinic N and graphitic N in the structure of nitrogen-doped graphene with the surfaces of Ni nanoparticles, should be pivotal to achieving the relatively high catalytic performance of materials. Due to its unique structure, the obtained Ni?NCF-700 catalyst with superhydrophobicity shows extraordinary performances toward the hydrogen transfer reaction of nitrobenzene and N-heterocycles in the aqueous state; meanwhile, it was also found that Ni?NCF-700 still retained its excellent catalytic activity and structural integrity after three cycles. Compared with traditional catalytic systems, our catalytic systems offer a highly effective, green and economical alternative for nitrobenzene and N-heterocycle transformation, and may open up a new avenue for simple construction of structure and activity defined carbon nanocomposite heterogeneous catalysts with superhydrophobicity.
Duan, Zhiying,Liu, Fangfang,Pang, Shaofeng,Su, Qiong,Wang, Yanbin,Xie, Xin,Zhang, Ping,Zhang, Yujing,Zhou, Feng
p. 1996 - 2010
(2020/04/07)

Copper(ii)-catalyzed c-n coupling of aryl halides and n-nucleophiles promoted by quebrachitol or diethylene glycol
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.
Chen, Guoliang,Chen, Yuanguang,Du, Fangyu,Fu, Yang,Wu, Ying,Zhou, Qifan
supporting information
p. 2161 - 2168
(2019/11/25)

Iron(II)-Based Metalloradical Activation: Switch from Traditional Click Chemistry to Denitrogenative Annulation
A unique concept for the intermolecular denitrogenative annulation of 1,2,3,4-tetrazoles and alkynes was discovered by using a catalytic amount of Fe(TPP)Cl and Zn dust. The reaction precludes the traditional, more favored click reaction between an organic azide and alkynes, and instead proceeds by an unprecedented metalloradical activation. The method is anticipated to advance access to the construction of important basic nitrogen heterocycles, which will in turn enable discoveries of new drug candidates.
Roy, Satyajit,Khatua, Hillol,Das, Sandip Kumar,Chattopadhyay, Buddhadeb
p. 11439 - 11443
(2019/07/17)

Palladium doping of In2O3 towards a general and selective catalytic hydrogenation of amides to amines and alcohols
Herein, the first general heterogeneous catalytic protocol for the hydrogenation of primary, secondary and tertiary amides to their corresponding amines and alcohols is described. Advantageously, this catalytic protocol works under additive-free conditions and is compatible with the presence of aromatic rings, which are fully retained in the final products. This hydrogenative C-N bond cleavage methodology is catalyzed by a Pd-doped In2O3 catalyst prepared by a microwave hydrothermal-assisted method followed by calcination. This catalyst displays highly dispersed Pd2+ ionic species in the oxide matrix of In2O3 that have appeared to be essential for its high catalytic performance.
Sorribes, Iván,Lemos, Samantha C. S.,Martín, Santiago,Mayoral, Alvaro,Lima, Renata C.,Andrés, Juan
p. 6965 - 6976
(2019/12/26)

A method for utilizing 2 - OP rectification residue preparing 2 - aminopyridine method (by machine translation)
The invention belongs to the field of organic chemistry, and in particular relates to a method for utilizing 2 - OP rectification residue preparing 2 - aminopyridine method, is a chemical by-product recycle of efficient utilization of the new method. Comprises the following steps: by phosphorylation zeolite and/or phosphorylated the silica gel for the 2 - OP rectification residue catalytic cracking of the role of the high-boiling, boiling residues depolymerized and into relatively low boiling point of pyridine - 2 - carboxamide, and the use of boiling point difference, by reduced pressure distillation method to make the pyridine - 2 - carboxamide with 2 - OP rectification residue the preliminary separation of high-boiling by the pyridine - 2 - carboxamide crude; under the protection of nitrogen, through the Huffman degradation by the reaction of 2 - aminopyridine crude product; the resulting 2 - aminopyridine crude product through the recrystallized or purified by distillation under reduced pressure. The invention through the "one-pot" will be its prepared pyridine - 2 - carboxamide crude product is converted into the 2 - aminopyridine method, in order to promote 2 - OP (i.e. 2 - cyano pyridine) of clean production and production process of the green, and to promote the efficient utilization of resources. (by machine translation)
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Paragraph 0018-0023

(2019/11/14)

Diverse Oxidative C(sp2)-N Bond Cleavages of Aromatic Fused Imidazoles for Synthesis of α-Ketoamides and N-(pyridin-2-yl)arylamides
An efficient and chemoselective C(sp2)-N bond cleavage of aromatic imidazo[1,2-a]pyridine molecules is developed. A broad scope of amide compounds such as α-ketoamides and N-(pyridin-2-yl)arylamides are afforded as the final products in up to quantitative yields. Diverse C-N bond cleavages are controlled by the oxidative species used in this transformation, with various amide products afforded in a chemoselective fashion. A preliminary study indicated that some α-ketoamides exhibit anti-Tobacco Mosaic Virus activity for potential use in plant protection.
Xu, Fangzhou,Wang, Yanyan,Xun, Xiwei,Huang, Yun,Jin, Zhichao,Song, Baoan,Wu, Jian
p. 8411 - 8422
(2019/05/17)

Copper-catalyzed arene amination in pure aqueous ammonia
A simple protocol for copper-catalyzed arene amination using aqueous ammonia without any additional ligands and organic coordinating solvents has been developed. The reaction pathway via a Cu(i)/Cu(iii) mechanism is proposed based on the results of control experiments as well as DFT calculations.
Takagi, Mio,Watanabe, Ayako,Murata, Shigeo,Takita, Ryo
supporting information
p. 1791 - 1795
(2019/02/20)

Starch functionalized creatine for stabilization of gold nanoparticles: Efficient heterogeneous catalyst for the reduction of nitroarenes
Selective reduction of nitroaromatic pollutants into amines with recoverable and reusable heterogeneous catalysts is highly desirable. Herein, we prepared and characterized an efficient novel catalyst comprising 4 nm size Au nanoparticles supported on creatine modified starch. Using this catalyst, efficient reduction of nitroarenes into amines at room temperature in aqueous media was achieved. The presence of creatine in the structure of the catalyst plays important role in amount of Au loading, efficiency of the catalyst, recycling times, and leaching of Au compared to starch supported Au without creatine.
Gholinejad, Mohammad,Dasvarz, Neda,Shojafar, Mohammad,Sansano, José M.
(2019/06/27)

Photocatalytic hydrogenation of nitroarenes: supporting effect of CoOx on TiO2 nanoparticles
Cobalt oxide visible light-active photo-catalysts supported on TiO2 nanoparticles with varying amount of cobalt oxide [3% CoOx/TiO2 (A), 4% CoOx/TiO2 (B), 5% CoOx/TiO2 (C)] were synthesized by solid-state method followed by calcination. The as-synthesized catalysts were characterized by various techniques such as powder XRD, TEM, EDX, UV-Vis-DRS and XPS analysis. The photocatalytic activity of the as-synthesized materials was studied for the reduction of nitroarenes to the corresponding amines using hydrazine monohydrate as the reductant. Cobalt(ii) oxide is responsible for the reduction of nitroarenes and then, cobalt(iii) is reduced back to the original compound by hydrazine hydrate, thus ascertaining the catalytic nature of this hydrogenation process. XPS suggests the presence of Co(ii) in CoOx/TiO2.
Amanchi, Srinivasa Rao,Ashok Kumar,Lakshminarayana, Bhairi,Satyanarayana,Subrahmanyam
p. 748 - 754
(2019/01/10)

BF3·SMe2 for Thiomethylation, Nitro Reduction and Tandem Reduction/SMe Insertion of Nitrogen Heterocycles
Herein, a general, solvent-free and straightforward thiomethylation of electron deficient heterocycles using BF3·SMe2 as a dual thiomethyl source and Lewis acidic activator is presented. A range of heterocycles including pyrimidine, pyrazine, pyridazine, thiazole and purine derivatives were successfully substituted using this method. An unexpected reductive property of BF3·SMe2 towards nitropyridines was also discovered including an intriguing tandem reduction/SMe insertion process in certain substrates. Notable features of the present work include its convenience and use of a non-malodorous reagent while the discovery of novel chemical transformations using BF3·SMe2 provides fundamental new insights into the reactivity of this commonly employed reagent.
S?derstr?m, Marcus,Zamaratski, Edouard,Odell, Luke R.
p. 5402 - 5408
(2019/06/27)

Synergistic Effects of ppm Levels of Palladium on Natural Clinochlore for Reduction of Nitroarenes
Augmenting the modified naturally occurring clay clinochlore with ppm amounts of palladium leads to a new and very effective reagent for the reduction of numerous aromatic nitro species. When palladium nanoparticles are supported on pyridyltriazole-modified clinochlore, iron within clinochlore acts synergistically with palladium to catalyze the reduction of a wide variety of nitroarenes at room temperature in aqueous media. Based on E-factor calculations, the catalyst system is found to be in line with green chemistry standards and can be recycled up to five times.
Gholinejad, Mohammad,Oftadeh, Erfan,Shojafar, Mohammad,Sansano, José M.,Lipshutz, Bruce H.
p. 4240 - 4248
(2019/09/06)

Ruthenium-Catalyzed Reductive Arylation of N-(2-Pyridinyl)amides with Isopropanol and Arylboronate Esters
A new three-component reductive arylation of amides with stable reactants (iPrOH and arylboronate esters), making use of a 2-pyridinyl (Py) directing group, is described. The N-Py-amide substrates are readily prepared from carboxylic acids and PyNH2, and the resulting N-Py-1-arylalkanamine reaction products are easily transformed into the corresponding chlorides by substitution of the HN-Py group with HCl. The 1-aryl-1-chloroalkane products allow substitution and cross-coupling reactions. Therefore, a general protocol for the transformation of carboxylic acids into a variety of functionalities is obtained. The Py-NH2 by-product can be recycled.
Ronson, Thomas O.,Renders, Evelien,Van Steijvoort, Ben F.,Wang, Xubin,Wybon, Clarence C. D.,Prokopcová, Hana,Meerpoel, Lieven,Maes, Bert U. W.
p. 482 - 487
(2019/01/04)

Syntheses, spectroscopy, electrochemistry, EPR, PXRD-structure and DFT/TD-DFT of bis[2-oxo-1-naphthaldehydato-κO,O’]copper(II)
Reaction of N-2-(R-pyridyl)-2-hydroxy-1-naphthaldimine {R = H (HL1), 4-CH3 (HL2) and 6-CH3 (HL3)} with copper(II) nitrate provides the new complex of bis[2-oxo-1-naphthaldehydato-κO,O’]copper(II) (1) via in-situ hydrolysis of the Schiff base back to 2-hydroxy-1-naphthaldehyde (HL′). Elemental analyses reveal that there are no nitrogen atoms in the complex. X-ray diffraction (PXRD) data indicate that the complex is monoclinic with space group P21/a and Z = 2 and that the ligand acts as bidentate through O?O-chelate system forming a bis-complex with O2O2-coordination sphere around the copper(II) ion. Electrochemical results show two quasi-reversible one electron charge transfer processes attributed to [Cu(L′)2]2?/[Cu(L′)2]? and [Cu(L′)2]?/[Cu(L′)2] (L’ = deprotonated aldehyde) couples in acetonitrile. The magnetic data confirm the paramagnetic property of the complex with one unpaired electron in the metallic centre. The results suggest that the complex assumes a geometry between tetrahedral and square-planar supported by DFT calculations. Thermal analysis shows an irreversible phase transformation from solid to isotropic liquid phase. EPR spectrum in chloroform exhibits an isotropic pattern with four lines due to nuclear hyperfine splitting from the copper(II) ion with spin 3/2. The structural analyses, electrochemical and paramagnetic properties of these complexes explore greater interests for their use in the supramolecular chemistry.
Enamullah, Mohammed,Joy, Baitul Alif,Islam, Mohammad Khairul
p. 56 - 64
(2018/09/18)

Simple Nickel Salts for the Amination of (Hetero)aryl Bromides and Iodides with Lithium Bis(trimethylsilyl)amide
Recent developments in the chemistry of C-N bond formation and the synthesis of anilines have allowed for the use of first-row transition metals to catalyze these transformations. Much of the progress in this area has been driven by comprehensive screening for privileged/tailored ligands, which can be costly and not readily available in a research laboratory setting. In this communication we report a protocol in which simple nickel salts catalyze the C-N cross-coupling reaction between (hetero)aryl bromides and iodides with lithium bis(trimethylsilyl)amide without the need for any additive ligand. This method is amenable to low nickel catalyst loadings (1%) as well as gram-scale reactions. Because of the good functional group tolerance and compatibility with heterocyclic moieties, this method is useful for academic laboratory settings where access to tailored ligands and noble-metal catalysts could be challenging.
Martinez, Gabriel Espinosa,Nugent, Joseph W.,Fout, Alison R.
supporting information
p. 2941 - 2944
(2018/09/21)

Development of a novel protocol for chemoselective deprotection of N/O-benzyloxycarbonyl (Cbz) at ambient temperature
Abstract: A novel protocol for the deprotection of N-benzyloxycarbonyl and O-benzyloxycarbonyl groups by nickel boride generated in situ from NaBH4 and NiCl2·6H2O in methanol at room temperature has been developed to give the corresponding amines and phenols. This protocol is chemoselective as groups like chloro, bromo, amide, ester, pyridine, and tert-butyloxycarbonyl moiety are unaffected under these conditions. The deprotection has also been validated in gram scale reactions, to establish the wider appropriateness of this protocol. Graphical abstract: [Figure not available: see fulltext.].
Saroha, Mohit,Aggarwal, Komal,Bartwal, Gaurav,Khurana, Jitender M.
p. 2231 - 2235
(2018/10/02)

An amine protecting group deprotectable under nearly neutral oxidative conditions
The 1,3-dithiane-based dM-Dmoc group was studied for the protection of amino groups. Protection was achieved under mild conditions for aliphatic amines, and under highly reactive conditions for the less reactive arylamines. Moderate to excellent yields were obtained. Deprotection was performed by oxidation followed by treating with a weak base. The yields were good to excellent. The new amino protecting group offers a different dimension of orthogonality in reference to the commonly used amino protecting groups in terms of deprotection conditions. It is expected to allow a collection of transformations to be carried out on the protected substrates that are unattainable using any known protecting groups.
Shahsavari, Shahien,McNamara, Chase,Sylvester, Mark,Bromley, Emily,Joslin, Savannah,Lu, Bao-Yuan,Fang, Shiyue
p. 1750 - 1757
(2018/08/21)

Visible-light-driven Efficient Photocatalytic Reduction of Organic Azides to Amines over CdS Sheet–rGO Nanocomposite
CdS sheet–rGO nanocomposite as a heterogeneous photocatalyst enables visible-light-induced photocatalytic reduction of aromatic, heteroaromatic, aliphatic and sulfonyl azides to the corresponding amines using hydrazine hydrate as a reductant. The reaction shows excellent conversion and chemoselectivity towards the formation of the amine without self-photoactivated azo compounds. In the adopted strategy, CdS not only accelerates the formation of nitrene through photoactivation of azide but also enhances the decomposition of azide to a certain extent, which entirely suppressed formation of the azo compound. The developed CdS sheet-rGO nanocomposite catalyst is very active, providing excellent results under irradiation with a 40 W simple household CFL lamp.
Singha, Krishnadipti,Mondal, Aniruddha,Ghosh, Subhash Chandra,Panda, Asit Baran
p. 255 - 260
(2018/01/15)

Synthesis, characterization, and application of easily accessible resin-encapsulated nickel nanocatalyst for efficient reduction of functionalized nitroarenes under mild conditions
Abstract: A novel resin-encapsulated nickel nanocatalyst has been synthesized by a modified impregnation method using nickel acetate tetrahydrate in presence of sodium borohydride as a mild reducing agent. The synthesized nanocatalyst was characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The concentration of nickel nanoparticles encapsulated on resin was determined by inductively coupled plasma-mass spectroscopy (ICP-MS). Further, synthesized resin-encapsulated nickel nanocatalyst was found to be stable and efficient in micromolar concentrations, for the selective reduction of functionalized nitroarenes to corresponding amines in good to high yield, under mild reaction conditions. The nanocatalyst shows excellent reusability. Graphical Abstract: SYNOPSIS A novel resin-encapsulated nickel nanocatalyst (Ni@XAD-4) was synthesized using a modified impregnation method. The nanocatalyst exhibited excellent catalytic activity towards the selective reduction of functionalized nitroarenes in the presence of NaBH 4 with reusability up to five cycles.[Figure not available: see fulltext.].
Rani, Poonam,Singh, Kamal Nain,Kaur, Amarjit
(2018/11/23)

Highly efficient aqueous phase reduction of nitroarenes catalyzed by phosphine-decorated polymer immobilized ionic liquid stabilized PdNPs
Palladium nanoparticles stabilized by lightly cross-linked phosphine-decorated polymer immobilized ionic liquids (PIIL) and their PEGylated counterparts (PEGPIIL) are highly effective catalysts for the aqueous phase hydrogenation and sodium borohydride-based reduction of a wide range of nitroaromatic and heteroaromatic compounds under mild conditions with low catalyst loadings. Introduction of extensive cross-linking with tris(4-vinylphenyl)phosphine to isolate the phosphine-based heteroatom and limit the number of surface Pd?P interactions did not have a significant influence on catalyst performance. Comparative testing revealed PdNPs immobilized on lightly cross-linked phsophine-decoarted PEGylated polymer to be a highly efficient catalyst for the aqueous phase reduction of nitroarenes with a TON of 36000 (TOF = 2580 h-1) for hydrogenation and a TON of 274000 (TOF = 17125 h-1) for transfer hydrogenation. Even though these reactions occur under diffusion control due the poor solubility of the substrate these values are the highest to be reported for the room temperature aqueous phase reduction of nitroarenes catalyzed by a nanoparticle-based system. A continuous flow reduction of nitrobenzene in a packed bed reactor operated over a period of 250 min with no sign of catalyst deactivation and the corresponding space-time-yield of 0.738 g L-1 min-1 is a marked improvement on that of 0.384 g L-1 min-1 obtained in batch. The same system also catalyzes a tandem Suzuki-Miyaura cross coupling-nitroarene reduction sequence to afford high yields of biaryl amine in an operationally straightforward single-pot procedure. This is a highly versatile protocol which will enable the aromatic nitro fragment to be introduced as a nitro-substituted aryl or heteroaryl halide and as such will lend itself to rapid diversification for the synthesis of a wide range of amines.
Doherty,Knight,Backhouse,Bradford,Saunders,Bourne,Chamberlain,Stones,Clayton,Lovelock
p. 1454 - 1467
(2018/03/13)

Synthesis and SAR of 4,5-dihydro-1H-pyrazolo[4,3-h]quinazoline derivatives as potent and selective CDK4/6 inhibitors
CDK4/6 pathway is an attractive target for development of anti-cancer drugs. Herein, we reported the design and synthesis of a series of 4,5-dihydro-1H-pyrazolo [4,3-h]quinazoline derivatives as selective CDK4/6 inhibitors. Applied with the optimizing strategy to the initial scaffold, it is found that compound 13n is able to selectively inhibit CDK4 and CDK6 with IC50 values 0.01 and 0.026 μM, respectively. The compound showed good anti-proliferative activity when tested in a panel of tumor cell lines with CDK4/6 related mechanism of action, the results clearly suggest that compound 13n works much better than Ly2385219 which is a selective CDK4/6 inhibitor. This compound was also found to have favorable pharmacokinetic parameters. Taken together, compound 13n could be selected for further preclinical evaluation.
Zhao, Hui,Hu, Xiaoxia,Cao, Kai,Zhang, Yue,Zhao, Kuantao,Tang, Chunlei,Feng, Bainian
p. 935 - 945
(2018/09/04)

Method for preparing aminopyridine from methylpyridine, and purifying method of aminopyridine
The invention relates to the field of organic synthesis, and concretely relates to a method for preparing aminopyridine from methylpyridine, and a purifying method of aminopyridine. Crude aminopyridine is prepared from corresponding methylpyridine through oxidation, esterification, hydrazinolysis and rearrangement reactions, the reaction yield of every step is high, and a post-treatment technology is easy to industrially operate; in the oxidation reaction, beta-cyclodextrin is used as a catalyst, so the conversion rate of the oxidation reaction is increased, and the generation of byproducts is reduced; and anhydrous ethanol and an alkane reagent are used to re-crystallize the crude aminopyridine, and a decolorizing agent is combined, and the purity of the final product reaches 98% or more; and the purifying method has the advantages of simplicity, easiness in operation, easily available raw materials, and suitableness for industrial production.
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(2017/09/01)

A palladium complex immobilized onto mesoporous silica: a highly efficient and reusable catalytic system for carbon–carbon bond formation and anilines synthesis
A palladium complex supported on functionalized mesoporous silica MCM-41 proved to be a highly efficient, recoverable catalyst for C–C coupling reactions and amination of aryl halides to afford anilines. The nanocatalyst was characterized by FT-IR spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, N2 adsorption–desorption isotherms and inductively coupled plasma analysis. The catalyst could be reused for several consecutive runs without significant loss of activity. The excellent yields of products, simple reaction procedures and short reaction times are the main advantages of this methodology.
Nikoorazm, Mohsen,Noori, Nourolah,Tahmasbi, Bahman,Faryadi, Sara
p. 469 - 481
(2017/07/12)

A new palladium complex supported on magnetic nanoparticles and applied as an catalyst in amination of aryl halides, Heck and Suzuki reactions
A simple, efficient and less expensive protocol for the phosphine-free C–C coupling reactions and synthesis of anilines in the presence of 2-aminobenzamide complex of palladium supported on Fe3O4 magnetic nanoparticles (Pd(0)-ABA-Fe3O4) has been reported. The Suzuki reaction was carried out in water or PEG using phenylboronic acid (PhB(OH)2) or sodium tetraphenyl borate (NaBPh4). Pd(0)-ABA-Fe3O4 has been found promising for Heck reaction of butyl acrylate, styrene or acrylonitrile with aryl halides (including Cl, Br and I). Also, Pd(0)-ABA-Fe3O4 has been found as efficient catalyst for the amination of aryl halides using aqueous ammonia. The products have been obtained in short reaction times and high yields. The catalyst was easily separated using an external magnet from the reaction mixture and reused for several runs without significant loss of its catalytic efficiency or palladium leaching. The leaching of catalyst has been examined by hot filtration and ICP-OES technique. The nanomagnetical catalyst was characterized by FTIR, TGA, XRD, VSM, TEM, SEM, EDS, DLS and ICP-OES techniques.
Ghorbani-Choghamarani, Arash,Tahmasbi, Bahman,Noori, Nourolah,Ghafouri-nejad, Raziyeh
p. 681 - 693
(2017/01/17)

Synthesis and Characterization of Pd(0)-SMT-MCM-41 and its Application in the Amination of Aryl Halides and Synthesis of 2,3-Dihydroquinazolin-4(1H)-Ones as Efficient and Recyclable Nanostructural Catalyst
Abstract: Palladium S-methylisothiourea [Pd(0)-SMT] has been grafted at the surface of functionalized mesoporous silica MCM-41 and used as an efficient and reusable heterogeneous nanocatalyst system for amination of various aryl halides and the one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives. The present methodology offers several advantages such as simplicity of procedure, easy isolation of the products and reused for several consecutive runs without significant loss of their catalytic efficiency. The characteristic structural features of this new catalyst was determined by various physico-chemical techniques such as FT-IR spectroscopy, XRD, SEM/EDS, ICP, TGA, BET surface area measurement and elemental analysis. Graphical Abstract: [Figure not available: see fulltext.]
Noori, Nourolah,Nikoorazm, Mohsen,Ghorbani-Choghamarani, Arash
p. 204 - 214
(2017/02/10)

A method for utilizing ammonia as raw material preparation fragrant primary amine synthetic method
The invention relates to a synthetic method for preparing primary arylamine by utilizing ammonia water as a raw material and in particular relates to a synthetic method for preparing primary arylamine through reaction among an aryl bromide, an aryl chloride and ammonia water. The method is characterized by using an aryl halide and ammonia water as the raw materials and a ferrite as a catalyst in a solvent and adopting microwave heating to react under the condition that no inorganic bases or ligands are adopted, thus obtaining the primary arylamine product. The method has the advantages that use of the ligands and the inorganic bases is avoided; the catalyst can be recycled; the method is simple and convenient to operate and is efficient.
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Paragraph 0021; 0027; 0028

(2017/08/25)

Development of a Leuckart-Wallach Reaction in Flow for the Synthesis of Abemaciclib
The development of a route for a key building block in the synthesis of abemaciclib is described. The route proceeds through a Leuckart-Wallach reductive amination in flow followed by an Ullmann amination with aqueous ammonia. Key to the Leuckart-Wallach reductive amination was the addition of trimethyl orthoformate for water removal, running the reaction continuously in a pipes-in-series reactor for rapid heat-up, and building a kinetic model to understand time and temperature parameters for the feed tank storage. The product of the Leuckart-Wallach reductive amination is forward processed in batch and telescoped with the Ullmann amination and subsequent workup. The development resulted in a robust process that has successfully been run on the production scale.
Frederick, Michael O.,Pietz, Mark A.,Kjell, Douglas P.,Richey, Rachel N.,Tharp, Gregg A.,Touge, Taichiro,Yokoyama, Naota,Kida, Michio,Matsuo, Toshiyasu
p. 1447 - 1451
(2017/09/22)

Glucose promoted facile reduction of azides to amines under aqueous alkaline conditions
A quick and efficient method for the reduction of azides to amines in water using d-glucose and KOH as green reagents is reported. The protocol is simple, inexpensive, scalable, and can be applied to different aromatic, heteroaromatic and sulphonyl azides. A high level of chemoselectivity is observed for azide reduction in the presence of other reducible functionalities like cyano, nitro, ether, ketone, amide and acid. The reaction gets completed in a short time (5-20 minutes), and furnishes the amines in high yield (85-99%). Unlike conventional hydrogenations, this reduction protocol does not require any metal catalyst, elaborate experimental setup or use of high-pressure equipment.
Chandna, Nisha,Kaur, Fatehjeet,Kumar, Shobhna,Jain, Nidhi
supporting information
p. 4268 - 4271
(2017/09/29)

A highly efficient heterogeneous copper-catalysed cascade reaction of aryl iodides with acetamidine hydrochloride leading to primary arylamines
A highly efficient heterogeneous copper-catalysed cascade reaction of aryl iodides with acetamidine hydrochloride was achieved in DMF in the presence of 10 mol% of an MCM-41-immobilised L-proline-copper(I) complex (MCM-41-L-proline-CuI) with Cs2CO3 as base, yielding a variety of primary arylamines in good to excellent yields. The new heterogeneous copper complex can be easily prepared from commercially readily available and inexpensive reagents, recovered by a simple filtration of the reaction solution and used at least seven more times without any decrease in activity.
Huang, Xue,Xiao, Ruian,You, Chongren,Yan, Tao,Cai, Mingzhong
p. 315 - 320
(2017/06/19)

Synthesis and characterization of magnetically nanoparticles of Fe3O4@APTMS@ZrCp2 as a novel and reusable catalyst for convenient reduction of nitro compounds with glycerol
The present paper describes the synthesis of magnetically nanoparticles of zirconocene-modified magnetite, Fe3O4@APTMS@ZrCp2, as a new generation in heterogeneous and reusable type nanocatalysts. The prepared zirconocene nanocomposite was characterized using FT-IR, SEM, XRD, EDX, AGFM, ICP–OES, TGA and BET analyses. The core–shell nanocatalyst exhibited an excellent catalytic activity towards glycerol reduction of various nitro compounds to the corresponding amines. All reactions were carried out in H2O at room temperature (40–90?min) to afford amines in high to excellent yields. Reusability of the core–shell zirconocene was examined 5 times without significant loss of its catalytic activity.
Zeynizadeh, Behzad,Sepehraddin, Farhad
p. 2649 - 2657
(2017/11/06)

PROCESS FOR THE CATALYTIC DIRECTED CLEAVAGE OF AMIDE-CONTAINING COMPOUNDS
The present invention relates to a catalytic method for the conversion of amide-containing compouds by means of a build-in directing group and upon the action of a heteronucleophilic compound (in se an amine (RNH2 or RNHR') or an alcohol (ROH) or a thiol (RSH)) in the presence of a metal catalyst to respectively esters, thioesters, carbonates, thiocarbonates and to what is defined as amide-containing compounds (such as carboxamides, urea, carbamates, thiocarbamates). The present invention also relates to these amide-containing compounds having a build-in directing group (DG), as well as the use of such directing groups in the catalytic directed cleavage of N-DG amides with the use of heteronucleophiles (in se an amine (RNH2 or RNHR') or an alcohol (ROH) or thiol (RSH)).
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Page/Page column 50

(2017/04/11)

Transfer Hydro-dehalogenation of Organic Halides Catalyzed by Ruthenium(II) Complex
A simple and efficient Ru(II)-catalyzed transfer hydro-dehalogenation of organic halides using 2-propanol solvent as the hydride source was reported. This methodology is applicable for hydro-dehalogenation of a variety of aromatic halides and α-haloesters and amides without additional ligand, and quantitative yields were achieved in many cases. The potential synthetic application of this method was demonstrated by efficient gram-scale transformation with catalyst loading as low as 0.5 mol %.
You, Tingjie,Wang, Zhenrong,Chen, Jiajia,Xia, Yuanzhi
p. 1340 - 1346
(2017/02/10)

One-pot synthesis of primary amines from carboxylic acids through rearrangement of in situ generated hydroxamic acid derivatives
A one-pot synthesis of primary amines from carboxylic acids through a Lossen rearrangement of hydroxamic acid derivatives, which were in situ generated by the reaction of carboxylic acids with O-trimethylsilylhydroxylamine (NH2OTMS) and carbonyl diimidazole (CDI, 1.5 equiv) in dimethyl sulfoxide at room temperature, has been achieved. This one-pot method could be applied to various carboxylic acids such as aromatic, heteroaromatic, aliphatic, and optically active substrates.
Hoshino, Yujiro,Ohtsuka, Naoya,Okada, Takuya,Honda, Kiyoshi
p. 5304 - 5307
(2016/11/16)