- SYNTHESIS, STRUCTURE, AND PROPERTIES OF 1-(p-R-PHENACYL)-2-(p-METHOXYBENZYLAMINO)PYRIDINIUM BROMIDES
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We have synthesized 2-(p-methoxybenzylamino)-1-(p-R-phenacyl)pyridinium bromides by alkylation of 2-(p-methoxybenzylamino)pyridine with substituted phenacyl bromides.Using spectral methods we have shown that the title compounds exist in the form of 1,2-diaryl-2-hydroxy-2,3-dihydroimidazopyridinium salts.We have studied their properties and suggest an alternative synthesis route.
- Demchenko, A. M.,Chumakov, V. A.,Nazarenko, K. G.,Krasovskii, A. N.,Pirozhenko, V. V.,Lozinskii, M. O.
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- ZnBr2 Mediated C?N Bond Formation using Cinnamyl Alcohol and 2-Amino Pyridines
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A simple method for C?N bond formation is disclosed by using cinnamyl alcohols and 2-amino pyridine derivatives in the presence of stoichiometric amount of zinc bromide. This reaction works with a wide range of substrates, and is compatible with primary, secondary, and homoallylic alcohols. To the best of our knowledge, this is the first report for C?N bond formation using cinnamyl alcohol and 2-amino pyridines using zinc bromide as a Lewis acid.
- Panigrahi, Ahwan,Ramaiah Prabhu, Kandikere,Sharanappa Sherikar, Mahadev
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- [(PPh3)2NiCl2]-Catalyzed C-N bond formation reaction via borrowing hydrogen strategy: Access to diverse secondary amines and quinolines
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Commercially available [(PPh3)2NiCl2] was found to be an efficient catalyst for the mono-N-alkylation of (hetero)- A romatic amines, employing alcohols to deliver diverse secondary amines, including the drug intermediates chloropyramine (5b) and mepyramine (5c), in excellent yields (up to 97%) via the borrowing hydrogen strategy. This method shows a superior activity (TON up to 10000) with a broad substrate scope at a low catalyst loading of 1 mol % and a short reaction time. Further, this strategy is also successful in accessing various quinoline derivatives following the acceptorless dehydrogenation pathway.
- Donthireddy,Pandey, Vipin K.,Rit, Arnab
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p. 6994 - 7001
(2021/06/09)
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- Ruthenium(ii) complexes with N-heterocyclic carbene-phosphine ligands for theN-alkylation of amines with alcohols
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Metal hydride complexes are key intermediates forN-alkylation of amines with alcohols by the borrowing hydrogen/hydrogen autotransfer (BH/HA) strategy. Reactivity tuning of metal hydride complexes could adjust the dehydrogenation of alcohols and the hydrogenation of imines. Herein we report ruthenium(ii) complexes with hetero-bidentate N-heterocyclic carbene (NHC)-phosphine ligands, which realize smart pathway selection in theN-alkylated reactionviareactivity tuning of [Ru-H] species by hetero-bidentate ligands. In particular, complex6cbwith a phenyl wingtip group and BArF?counter anion, is shown to be one of the most efficient pre-catalysts for this transformation (temperature is as low as 70 °C, neat conditions and catalyst loading is as low as 0.25 mol%). A large variety of (hetero)aromatic amines and primary alcohols were efficiently converted into mono-N-alkylated amines in good to excellent isolated yields. Notably, aliphatic amines, challenging methanol and diamines could also be transformed into the desired products. Detailed control experiments and density functional theory (DFT) calculations provide insights to understand the mechanism and the smart pathway selectionvia[Ru-H] species in this process.
- Huang, Ming,Li, Yinwu,Lan, Xiao-Bing,Liu, Jiahao,Zhao, Cunyuan,Liu, Yan,Ke, Zhuofeng
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supporting information
p. 3451 - 3461
(2021/05/03)
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- Convenient and Reusable Manganese-Based Nanocatalyst for Amination of Alcohols
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The development of new sustainable nanocatalytic systems for green chemical synthesis is a growing area in chemical science. Herein, a reusable heterogeneous N-doped graphene-based manganese nanocatalyst (Mn@NrGO) for selective N-alkylation of amines with alcohols is described. Mechanistic studies illustrate that the catalytic reaction follows a domino dehydrogenation-condensation-hydrogenation sequence of alcohols and amines with the formation of water as the sole by-product. The scope of the reaction is extended to the synthesis of pharmaceutically important N-alkylated amine intermediates. The heterogeneous nature of the catalyst made it easy to separate for long-term performance, and the recycling study revealed that the catalyst was robust and retained its activity after several recycling experiments.
- Subaramanian, Murugan,Ramar, Palmurukan M.,Sivakumar, Ganesan,Kadam, Ravishankar G.,Petr, Martin,Zboril, Radek,Gawande, Manoj B.,Balaraman, Ekambaram
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p. 4334 - 4341
(2021/08/25)
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- Water-promoted dehydrative coupling of 2-aminopyridines in heptane: Via a borrowing hydrogen strategy
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A synthetic method for dehydrative N-benzylation promoted by water molecules in heptane using a π-benzylpalladium system has been developed. The presence of water significantly accelerates carbon-nitrogen bond formation, which is accomplished in an atom-economical process to afford the corresponding N-monobenzylated products. A crossover experiment afforded H/D scrambled products, which is consistent with a borrowing hydrogen mechanism. Kinetic isotope effect measurements revealed that benzylic carbon-hydrogen bond cleavage was the rate-determining step.
- Azumaya, Isao,Hikawa, Hidemasa,Kikkawa, Shoko,Nakayama, Taku
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p. 23144 - 23150
(2021/07/21)
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- Designed pincer ligand supported Co(ii)-based catalysts for dehydrogenative activation of alcohols: Studies onN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines
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Base-metal catalystsCo1,Co2andCo3were synthesized from designed pincer ligandsL1,L2andL3having NNN donor atoms respectively.Co1,Co2andCo3were characterized by IR, UV-Vis. and ESI-MS spectroscopic studies. Single crystal X-ray diffraction studies were investigated to authenticate the molecular structures ofCo1andCo3. CatalystsCo1,Co2andCo3were utilized to study the dehydrogenative activation of alcohols forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines. Under optimized reaction conditions, a broad range of substrates including alcohols, anilines and ketones were exploited. A series of control experiments forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines were examined to understand the reaction pathway. ESI-MS spectral studies were investigated to characterize cobalt-alkoxide and cobalt-hydride intermediates. Reduction of styrene by evolved hydrogen gas during the reaction was investigated to authenticate the dehydrogenative nature of the catalysts. Probable reaction pathways were proposed forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines on the basis of control experiments and detection of reaction intermediates.
- Singh, Anshu,Maji, Ankur,Joshi, Mayank,Choudhury, Angshuman R.,Ghosh, Kaushik
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p. 8567 - 8587
(2021/06/30)
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- N-Alkylation of Amines with Alcohols Catalyzed by Manganese(II) Chloride or Bromopentacarbonylmanganese(I)
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A manganese-catalyzed N-alkylation reaction of amines with alcohols via hydrogen autotransfer strategy has been demonstrated. The developed practical catalytic system including an inexpensive, nontoxic, commercially available MnCl2 or MnBr(CO)5 as the metal salt and triphenylphosphine as a ligand provides access to diverse aromatic, heteroaromatic, and aliphatic secondary amines in moderate-to-high yields. In addition, this operationally simple protocol is scalable to the gram level and suitable for synthesizing heterocycles such as indole and resveratrol-derived amines known to be active for Alzheimer's disease.
- Wei, Dongyue,Yang, Peng,Yu, Chuanman,Zhao, Fengkai,Wang, Yilei,Peng, Zhihua
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p. 2254 - 2263
(2021/02/26)
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- Ru(II)-NHC catalysed N-Alkylation of amines with alcohols under solvent-free conditions
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The reaction of [RuCl2(p-cymene)]2 with in situ prepared Ag-N-heterocyclic carbene (NHC) complexes yields a series of [RuCl2(p-cymene)(NHC)] complexes (2). All of the complexes have been characterised by elemental analysis, and 1H NMR and 13C NMR spectroscopies. These complexes have been tested for the N-alkylation of aromatic amines with arylmethyl alcohols under neat conditions in the presence of KOtBu at 120 °C. Compounds (2) are stable and have high catalytic/selective activity for the N-alkylation reactions of primary amines to afford secondary amines.
- Karaca, Emine ?zge,Dehimat, Zieneb Imene,Ya?ar, Sedat,Gürbüz, Nevin,Tebbani, Dahmane,?etinkaya, Bekir,?zdemir, ?smail
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- Half-sandwich Ru(ii) arene complexes bearing benzimidazole ligands for theN-alkylation reaction of aniline with alcohols in a solvent-free medium
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In this article, the directN-alkylation reactions of amines with alcohol derivatives using the borrowing hydrogen methodology have been investigated. For this purpose, a new series of half-sandwich ruthenium(ii) complexes bearing N-coordinated benzimidazole complexes have been synthesized and fully characterized by FT-IR,1H NMR and13C NMR spectroscopies. Additionally, the structures of the complexes2a-2ehave been characterized by X-ray crystallography. All new complexes were investigated for their catalytic activities in the alkylation reaction of amines with alcohol derivatives. It was found that alkylation reactions in a solvent-free medium are efficient and selective.
- ?i?ek, Metin,Gürbüz, Nevin,?zdemir, Nam?k,?zdemir, ?smail,?spir, Esin
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p. 11075 - 11085
(2021/07/02)
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- Effect of the ancillary ligand in N-heterocyclic carbene iridium(III) catalyzed N-alkylation of amines with alcohols
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A series of air-stable N-heterocyclic carbene (NHC) Ir(III) complexes (Ir1-6), bearing various combinations of chlorine, pyridine and NHC ligands, were assayed for the N-alkylation of amines with alcohols. It was found that Ir3, with two monodentate 1,3-bis-methyl-imidazolylidene (IMe) ligands, emerged as the most active complex. A large variety of amines and primary alcohols were efficiently converted into mono-N-alkylated amines in 53–96% yields. As a special highlight, for the challenging MeOH, selective N-monomethylation could be achieved using KOH as a base under an air atmosphere. Moreover, this catalytic system was successfully applied to the gram-scale synthesis of some valuable compounds.
- Feng, Xinshu,Huang, Ming
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- Active ruthenium(II)-NHC complexes for alkylation of amines with alcohols using solvent-free conditions
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A series of new ruthenium(II) complexes bearing N-heterocyclic carbene ligands with benzylic groups were prepared by transmetallation reactions between silver(I) N-heterocyclic carbene complexes and [RuCl2(p-cymene)]2. All of the obtained complexes were characterized by FT-IR, 1H NMR and 13C NMR spectroscopy, and the molecular structure of compound 3c was also determined by X-ray crystallography. These ruthenium complexes were tested for the alkylation of aromatic amines with a wide range of primary alcohols under solvent-free conditions using the hydrogen borrowing strategy. All of the compounds tested here showed excellent catalytic activity for these reactions and N-monoalkylated products were obtained selectively using 2.5 mol% of the ruthenium complexes.
- Yi?it, Beyhan,?zge Karaca, Emine,Yi?it, Murat,Gürbüz, Nevin,Arslan, Hakan,?zdemir, ?smail
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- Nickel(II)-NΛNΛO Pincer Type Complex-Catalyzed N-alkylation of Amines with Alcohols via the Hydrogen Autotransfer Reaction
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A highly sustainable catalytic protocol for the coupling of alcohols and amines for selective monoalkylated amines using Ni(II)-NΛNΛO pincer type complexes through the borrowing hydrogen methodology is described. An array of Ni(II) catalysts (1-3) was synthesized and characterized by various spectral and analytical methods. Furthermore, the distorted square planar geometry of the complexes (1 and 2) was substantiated with single crystal X-ray diffraction study. The inexpensive nickel-based catalytic methodology displays a broad substrate scope for the N-alkylation of aromatic and heteroaromatic amines using a diverse range of primary alcohols with excellent yields up to 97%. The present approach is environmentally benign, which liberates water as the sole byproduct. A short synthesis of drug intermediates such as mepyramine and chloropyramine illustrates the utility of the present protocol.
- Balamurugan, Gunasekaran,Ramesh, Rengan,Malecki, Jan Grzegorz
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p. 7125 - 7135
(2020/06/08)
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- First used of Alkylbenzimidazole-Cobalt(II) complexes as a catalyst for the N-Alkylation of amines with alcohols under solvent-free medium
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In this study, alkylbenzimidazole-cobalt(II)-catalyzed direct N-alkylation reactions of amines with alcohols derivatives have been investigated under solvent-free medium. For this purpose, a series of cobalt(II) complexes bearing N-alkylbenzimidazole complexes have been synthesized and novel complexes fully characterized by elemental analysis, FT-IR, 1H NMR and, 13C{1H} NMR spectroscopies. Also, the structure of the complex 2a has been confirmed by X-ray crystallography. Generally, the N-alkylating reaction is usually performed in toluene with various metal complexes including cobalt. In this catalytic study of complexes, 2a-c has carried out in without solvent and alcohol acted both as solvent and reactant. Conversion and selectivity of amine products according to imine products for alkylation reactions have been seen high yield in medium solvent-free relative to in toluene.
- ?zdemir, ?smail,?zdemir, Nam?k,?ahin, Neslihan,Gürbüz, Nevin,Y?ld?r?m, ?lkay
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- Solvent-Free N-Alkylation and Dehydrogenative Coupling Catalyzed by a Highly Active Pincer-Nickel Complex
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The synthesis and characterization of a pincer-nickel complex of the type (iPr2NNN)NiCl2(CH3CN) is reported here. We have demonstrated the utility of this pincer-nickel complex (0.02 and 0.002 mol %) for the catalytic N-alkylation of amines using various alcohols. Under solvent-free conditions, while the highest yield (ca. 90%) was obtained for the alkylation of 2-aminopyridine with naphthyl-1-methanol, excellent turnovers (34000 TONs) were observed for the alkylation of 2-aminopyridine with 4-methoxybenzyl alcohol. To demonstrate the synthetic utility of these systems, high-yield reactions (up to 98%) have been probed for representative substrates with a higher loading of the pincer-nickel catalyst (4 mol %). DFT studies indicate that while β-hydride elimination is the RDS for alcohol dehydrogenation, the N-alkylated product can be formed either via hydrogenation with a rate-determining σ-bond metathesis or by alcoholysis that has imine insertion as the RDS. All of the corresponding resting states have been observed by HRMS (ESI) analysis. The labeling experiments are also complementary to DFT studies and show evidence for the involvement of the benzylic C-H bond in the RDS with a kCHH/kCHD value of about 2.5. This method has been applied to accomplish efficient (2000 TONs) dehydrogenative coupling leading to various benzimidazoles.
- Arora, Vinay,Dutta, Moumita,Das, Kanu,Das, Babulal,Srivastava, Hemant Kumar,Srivastava, Hemant Kumar,Kumar, Akshai,Kumar, Akshai
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p. 2162 - 2176
(2020/06/05)
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- Novel N-Alkylbenzimidazole-Ruthenium (II) complexes: Synthesis and catalytic activity of N-alkylating reaction under solvent-free medium
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In this article, direct N-alkylation reactions of amines with alcohols derivatives have been investigated. For this purpose, a new series ruthenium (II) complexes bearing N-coordinated benzimidazole complexes with have been synthesized and fully characterized by elemental analysis, FT-IR, 1H NMR and, 13C NMR spectroscopies. Additionally, the structures of the complexes 2b and 2c have been confirmed by X-ray crystallography. Although the N-alkylating reaction is usually performed in toluene, the catalytic study of complexes 2a-d has carried out no additional solvent and alcohol acted both as solvent and reactant of alkylating by using a little excess of alcohols. Surprisingly, conversion and selectivity of amine product for alkylation reaction have been seen high in medium solvent-free relative to in toluene.
- ?ahin, Neslihan,?zdemir, Nam?k,Gürbüz, Nevin,?zdemir, ?smail
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- A borrowing hydrogen methodology: Palladium-catalyzed dehydrative: N -benzylation of 2-aminopyridines in water
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We demonstrate a greener borrowing hydrogen methodology using the π-benzylpalladium system, which offers an efficient and environmentally friendly dehydrative N-monobenzylation of 2-aminopyridines with benzylic alcohols in the absence of base. The crossover experiment using benzyl-α,α-d2 alcohol and 3-methylbenzyl alcohol afforded H/D scrambled products, suggesting that the dehydrative N-benzylation in our catalytic system involves a borrowing hydrogen pathway. KIE experiments show that C-H bond cleavage at the benzylic position of benzyl alcohol is involved in the rate-determining step (KIE = 2.9). This simple base-free protocol can be achieved under mild conditions in an atom-economic process, affording the desired products in moderate to excellent yields.
- Hikawa, Hidemasa,Imamura, Hirokazu,Kikkawa, Shoko,Azumaya, Isao
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supporting information
p. 3044 - 3049
(2018/07/13)
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- Unsymmetrical indazolyl-pyridinyl-triazole ligand-promoted highly active iridium complexes supported on hydrotalcite and its catalytic application in water
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Herein, an indazolyl-pyridinyl-triazole ligand was synthesized and its iridium complex supported on hydrotalcite was characterized via X-ray power diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) spectroscopy and transmission electron microscopy (TEM). This new heterogeneous catalyst bearing the unsymmetrical indazolyl-pyridinyl-triazole ligand exhibits high catalytic activity in water. Both functionalized amines and imines were obtained from the challenging selective reaction of benzylamines with arylamines through transfer hydrogenation and dehydrogenation under clean conditions. In particular, it was observed that this catalyst system showed good recovery performance in water. Mechanistic studies showed that this transformation occurs via amine dehydrogenation, hydrolysis and condensation processes. The direct capture of the reaction intermediate provides sufficient proof for this process.
- Ge, Chenyang,Sang, Xinxin,Yao, Wei,Zhang, Liang,Wang, Dawei
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supporting information
p. 1805 - 1812
(2018/04/30)
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- An Efficient Homogenized Ruthenium(II) Pincer Complex for N-Monoalkylation of Amines with Alcohols
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An ionic 2,6-bis(imidazo[1,2-α]pyridin-2-yl)pyridine-based N^N^N pincer ruthenium(II) complex exhibited high efficiency in the C–N bond formation between amines and alcohols by the “borrowing hydrogen” (BH) or “hydrogen autotransfer” (HA) concept. The synthetic protocol selectively generated monoalkylated amines without formation of tertiary amines during the reaction. The unique selectivity enabled the formation of symmetrically and asymmetrically substituted diamines. This methodology features several advantages including a low catalyst loading (as low as 0.5 mol-%), a short reaction time (as short as 2 h), and excellent N-monoalkylation selectivity.
- Yang, Fa-Liu,Wang, Ying-Hui,Ni, Yong-Feng,Gao, Xiang,Song, Bing,Zhu, Xinju,Hao, Xin-Qi
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p. 3481 - 3486
(2017/07/04)
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- An Efficient and Selective Nickel-Catalyzed Direct N-Alkylation of Anilines with Alcohols
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Herein, we developed an efficient and selective nickel-catalyzed monoalkylation of various primary alcohols with aryl and heteroaryl amines together with diols and amino alcohol derivatives. Notably, the catalytic protocol consisting of an earth-abundant and non-precious NiBr2/L1 system enables the transformations in the presence of hydroxyl, alkene, nitrile, and nitro functionalities. As a highlight, we have demonstrated the alkylation of diamine, intramolecular cyclization to N-heterocycles, and functionalization of complex vitamin E, an (±)-α-tocopherol derivative. Preliminary mechanistic studies revealed the participation of a benzylic C-H bond in the rate-determining step.
- Vellakkaran, Mari,Singh, Khushboo,Banerjee, Debasis
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p. 8152 - 8158
(2017/12/08)
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- Efficient and practical catalyst-free-like dehydrative N-alkylation of amines and sulfinamides with alcohols initiated by aerobic oxidation of alcohols under air
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We developed simple and practical N-alkylation reactions of amines and sulfinamides with primary and secondary alcohols by using only catalytic amounts of air as the initiator without adding any external catalysts. This method has advantages of simple conditions, easy operation, and comparatively wider scope of substrates, providing an efficient and green catalyst-free-like alcohol-based dehydrative N-alkylation method. Mechanistic studies revealed that air initiated the reactions by aerobic oxidation of the alcohols to the key initiating aldehydes or ketones in the presence of bases.
- Li, Xiaohui,Li, Shuangyan,Li, Qiang,Dong, Xu,Li, Yang,Yu, Xiaochun,Xu, Qing
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supporting information
p. 264 - 272
(2015/12/30)
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- Heteroleptic binuclear copper(I) complexes bearing bis(salicylidene)hydrazone ligands: Synthesis, crystal structure and application in catalytic N-alkylation of amines
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A new series of heteroleptic binuclear Cu(I) bis(salicylidene)hydrazone complexes (1-4) bearing triphenylphospine coligands have been synthesized from the reactions of copper(II) precursor complex [CuCl2(PPh3)2] with oxadiazole compounds A-D, respectively. It has been observed that the oxadiazole compounds undergo ring cleavage with in situ reduction of Cu(II) ion, during the formation of complexes (1-4). The oxadiazoles (A-D) and the Cu(I) complexes (1-4) have been characterized by analytical and spectroscopic methods. Single crystal X-ray diffraction study of complex 2 has revealed a distorted tetrahedral geometry around each Cu(I) center. Catalytic efficiency of the new complexes on the N-alkylation of amines using alcohols was studied under optimized conditions. The new complexes have also been tested for their catalytic activity towards the direct N-alkylation of 2-nitropyridine.
- Prakash, Govindan,Nirmala, Muthukumaran,Ramachandran, Rangasamy,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz,Sanmartin, Jesus
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- Ruthenium(II) complexes containing a phosphine-functionalized thiosemicarbazone ligand: Synthesis, structures and catalytic C-N bond formation reactions via N-alkylation
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A series of ruthenium(II) complexes incorporating a thiosemicarbazone chelate tethered with a diphenylphosphine pendant have been studied. Thus, [(PNS-Et)RuCl(CO)(PPh3)] (1), [N,S-(PNS-Et)RuH(CO)(PPh3)2] (2) and [(PNS-Et)RuCl(PPh3)] (3) were synthesized by reactions of various RuII precursors with 2-(2-(diphenylphosphino)benzylidene)-N-ethylthiosemicarbazone (PNS-Et). However, complexation of PNS-Et with an equimolar amount of [RuCl2(dmso)4] resulted in two different entities [(PNS-Et)RuCl(dmso)2] (4) and [(PNS-Et)2Ru] (5) with different structural features in a single reaction. All the RuII complexes have been characterized by analytical and various spectroscopic techniques. Compounds 1-5 were recrystallized, and the X-ray crystal structures have been reported for 1, 2 and 5. In the complexes 1 and 3-5 the ligand coordinated in a tridentate monobasic fashion by forming PNS five- and six-membered rings, whereas in 2, the ligand coordinated in a bidentate monobasic fashion by forming a strained NS four-membered ring. Furthermore, compounds 1-5 showed catalytic activity in N-alkylation of heteroaromatic amines. Notably, complexes 1-3 were found to be very efficient catalysts toward N-alkylation of a wide range of heterocyclic amines with alcohols. In the presence of a catalytic amount of 2 with 50 mol% of KOH, N1,C5-dialkylation of 4-phenylthiazol-2-amine has been investigated. Reaction of in situ generated aldehyde with amine yields the N1,C5-dialkylated products through the hydride ion transformation from alcohol. Complexes 1-3 also catalyzed a variety of coupling reactions of benzyl alcohols and sulfonamides, which were realized often with 99% isolated yields. Advantageously, only one equivalent of the primary alcohol was consumed in the process.
- Ramachandran, Rangasamy,Prakash, Govindan,Selvamurugan, Sellappan,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz,Linert, Wolfgang,Gusev, Alexey
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p. 11405 - 11422
(2015/03/05)
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- Ruthenium(II) carbonyl complexes designed with arsine and PNO/PNS ligands as catalysts for N-alkylation of amines via hydrogen autotransfer process
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A series of phosphine-functionalized hydrazone/thiosemicarbazone ligands and their corresponding ruthenium(II) carbonyl complexes of the type [RuCl(CO)(AsPh3)(L)] (1-5) [L = 2-(2-(diphenylphosphino)benzylidene)benzoic acid hydrazone (PNO-BHy), 2-(2-(diphenylphosphino)benzylidene)nicotinic acid hydrazone (PNO-NHy), 2-(2-(diphenylphosphino)benzylidene)-2-furoic hydrazone (PNO-FHy), 2-(2-(diphenylphosphino)benzylidene)-4-ethyl-3-thiosemicarbazone (PNS-EtTs), 2-(2-(diphenylphosphino)benzylidene)-4-cyclohexyl-3-thiosemicarbazone (PNS-CyTs)] have been synthesized based on the ligands with different electronic and steric effects. These complexes were characterized by elemental analyses and various spectral methods. The solid-state structure of the complex 4 was determined by single-crystal X-ray diffraction method. In all of the complexes, the ligand was bound to the Ru(II) center via the PNO/PNS donor atoms. All the ruthenium(II) complexes were demonstrated as highly efficient catalysts for the synthesis of secondary amines/amides by the coupling of primary amines/amides with alcohols at low catalyst loading, and the maximum yield was obtained up to 98%. The N-alkylation reaction can be readily carried out under moderate conditions, and release of water is the sole byproduct. In addition, the effects of substituents on the ligand, solvents, base and catalyst loading on the catalytic activity of the complexes have been investigated. Advantageously, only one equivalent of the alcohol was consumed in the process.
- Ramachandran, Rangasamy,Prakash, Govindan,Nirmala, Muthukumaran,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz
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supporting information
p. 130 - 140
(2015/06/22)
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- Efficient and versatile catalysis of N-alkylation of heterocyclic amines with alcohols and one-pot synthesis of 2-aryl substituted benzazoles with newly designed ruthenium(ii) complexes of PNS thiosemicarbazones
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Ruthenium(ii) carbonyl complexes with phosphine-functionalized PNS type thiosemicarbazone ligands [RuCl(CO)(EPh3)(L)] (1-6) (E = P or As, L = 2-(2-(diphenylphosphino)benzylidene) thiosemicarbazone (PNS-H), 2-(2-(diphenylphosphino)benzylidene)-N-methylthiosemicarbazone (PNS-Me), 2-(2-(diphenylphosphino)benzylidene)-N-phenylthiosemicarbazone (PNS-Ph)) have been synthesized and characterized by elemental analysis and spectroscopy (IR, UV-Vis, 1H, 13C, 31P-NMR) as well as ESI mass spectrometry. The molecular structures of complexes 1, 2 and 6 were identified by means of single-crystal X-ray diffraction analysis. The analysis revealed that all the complexes possess a distorted octahedral geometry with the ligand coordinating in a uni-negative tridentate PNS fashion. All the ruthenium complexes (1-6) were tested as catalyst for N-alkylation of heteroaromatic amines with alcohols. Notably, complex 2 was found to be a very efficient and versatile catalyst towards N-alkylation of a wide range of heterocyclic amines with alcohols. Complex 2 can also catalyze the direct amination of 2-nitropyridine with benzyl alcohol to the corresponding secondary amine. Furthermore, a preliminary examination of performance for N,N-dialkylation of diamine showed promising results, giving good conversion and high selectivity. In addition, N-alkylation of ortho-substituted anilines (-NH2, -OH and -SH) led to the one-pot synthesis of 2-aryl substituted benzimidazoles, benzoxazoles and benzothiazoles, also revealing the catalytic activity of complex 2. This journal is the Partner Organisations 2014.
- Ramachandran, Rangasamy,Prakash, Govindan,Selvamurugan, Sellappan,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz,Ramkumar, Venkatachalam
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supporting information
p. 7889 - 7902
(2014/05/20)
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- A metal-free tandem demethylenation/C(sp2)-H cycloamination process of N -Benzyl-2-aminopyridines via C-C and C-N bond cleavage
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A mild, metal-free synthesis of pyrido[1,2-a]benzimidazoles starting with N-benzyl-2-aminopyridines, which employs PhI(OPiv)2 as a stoichiometric oxidant, has been developed. The process is initiated by an unusual PhI(OPiv)2-mediated ipso SEAr reaction, followed by solvent-assisted C-C and C-N bond cleavage.
- Liang, Dongdong,He, Yimiao,Liu, Lanying,Zhu, Qiang
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p. 3476 - 3479
(2013/07/26)
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- Palladium-catalyzed N-alkylation of amides and amines with alcohols employing the aerobic relay race methodology
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Possibly because homogeneous palladium catalysts are not typical borrowing hydrogen catalysts and ligands are thus ineffective in catalyst activation under conventional anaerobic conditions, they had not been used in the N-alkylation reactions of amines/amides with alcohols in the past. By employing the aerobic relay race methodology with Pd-catalyzed aerobic alcohol oxidation being a more effective protocol for alcohol activation, ligand-free homogeneous palladiums are successfully used as active catalysts in the dehydrative N-alkylation reactions, giving high yields and selectivities of the alkylated amides and amines. Mechanistic studies implied that the reaction most probably proceeds via the novel relay race mechanism we recently discovered and proposed. By employing the aerobic relay race methodology with Pd-catalyzed aerobic alcohol oxidation being a more effective protocol for alcohol activation, ligand-free homogeneous palladiums are successfully used as active catalysts in the dehydrative N-alkylation reactions of amines and amides with alcohols, giving high yields and selectivities of the alkylated amines and amides. Mechanistic studies implied that the reaction most probably proceeds via the novel relay race mechanism we recently discovered and proposed. Copyright
- Yu, Xiaochun,Jiang, Lan,Li, Qiang,Xu, Qing,Xie, Yuanyuan
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p. 2322 - 2332,11
(2020/09/16)
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- Ni-Cu/γ-Al2O3 catalyzed N-alkylation of amines with alcohols
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A γ-Al2O3 supported Ni and Cu bimetallic nanoparticles catalyst (45 wt.% Ni, Ni/Cu mass ratio = 4.5/1.0) is prepared by electroless plating method for the N-alkylation of amines with alcohols under base and Lewis acidic cocatalyst conditions. The catalyst afforded fast conversions, high selectivity for amines and alcohols with various structures under an Ar atmosphere in o-xylene. Furthermore, catalyst still has a stable catalytic activity after two consecutive cycles regenerated.
- Sun, Jian,Jin, Xiaodong,Zhang, Fengwei,Hu, Wuquan,Liu, Juntao,Li, Rong
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experimental part
p. 30 - 33
(2012/07/17)
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- Impregnated ruthenium on magnetite as a recyclable catalyst for the N-alkylation of amines, sulfonamides, sulfinamides, and nitroarenes using alcohols as electrophiles by a hydrogen autotransfer process
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Various impregnated metallic salts on magnetite have been prepared, including cobalt, nickel, copper, ruthenium, and palladium salts, as well as a bimetallic palladium - copper derivative. Impregnated ruthenium catalyst is a versatile, inexpensive, and simple system for the selective N-monoalkylation of amino derivatives with poor nucleophilic character, such as aromatic and heteroaromatic amines, sulfonamides, sulfinamides, and nitroarenes, using in all cases alcohols as the initial source of the electrophile, through a hydrogen autotransfer process. In the case of sulfinamides, this is the first time that these amino compounds have been alkylated following this strategy, allowing the use of chiral sulfinamides and secondary alcohols to give the alkylated compound with a diastereomeric ratio of 92:8. In these cases, after alkylation, a simple acid deprotection gave the expected primary amines in good yields. The ruthenium catalyst is quite sensitive, and small modifications of the reaction medium can change the final product. The alkylation o amines using potassium hydroxide renders the N-monoalkylated amines, and the same protocol using sodium hydroxide yields the related imines. The catalyst can be easily removed by a simple magnet and can be reused up to ten times, showing the same activity.
- Cano, Rafael,Ramon, Diego J.,Yus, Miguel
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experimental part
p. 5547 - 5557
(2011/08/10)
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- Palladium(II) acetate as catalyst for the N-alkylation of aromatic amines, sulfonamides, and related nitrogenated compounds with alcohols by a hydrogen autotransfer process
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Palladium(II) acetate is a versatile, inexpensive, and simple catalyst for the selective N-monoalkylation of amino derivatives with poor nucleophilic character, such as aromatic and heteroaromatic amines as well as carboxamides, sulfonamides, and phosphazenes, using, in all cases, primary alcohols as the initial source of the electrophile, through a hydrogen autotransfer process. The regioselectivity of the benzothiazol-2-amine alkylation is contrary to that found using halogenated electrophiles.
- Martinez-Asencio, Ana,Yus, Miguel,Ramon, Diego J.
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experimental part
p. 3730 - 3740
(2011/12/21)
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- Manganese dioxide catalyzed N-alkylation of sulfonamides and amines with alcohols under air
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By simply running the reactions under air and solvent-free conditions using catalytic amounts of manganese dioxide, a practical and efficient N-alkylation method for a variety of sulfonamides and amines using alcohols as green alkylating reagents was developed.
- Yu, Xiaochun,Liu, Chuanzhi,Jiang, Lan,Xu, Qing
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supporting information; experimental part
p. 6184 - 6187
(2012/01/06)
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- Impregnated palladium on magnetite as catalyst for multicomponent reductive amination reactions and other related reducing processes
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The impregnated palladium on magnetite catalyst is a versatile system for different reduction processes using inexpensive polymehtylhydrosiloxane, including multicomponent reductive amination reactions, and aldehyde, imine, sulfinimide and sulfoxide reductions. This catalyst avoids the use of any type of expensive and quite expensive organic ligand, showing excellent yields, under mild reaction conditions. The catalyst is easily removed from the reaction medium, just by using a magnet. The catalytic system is very selective permitting the discrimination between ketones and aldehydes in the reductive amination process.
- Cano, Rafael,Yus, Miguel,Ramón, Diego J.
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experimental part
p. 8079 - 8085
(2011/11/04)
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- N-Alkylation of poor nucleophilic amine and sulfonamide derivatives with alcohols by a hydrogen autotransfer process catalyzed by copper(II) acetate
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Copper(II) acetate is a versatile, cheap, and simple catalyst for the selective N-monoalkylation of amino derivatives with poor nucleophilic character, such as aromatic and heteroaromatic amines as well as sulfonamides, using in all cases primary alcohols as initial source of the electrophiles, through a hydrogen autotransfer process. In the case of sulfonamides, the monoalkylation process followed by a naphthalene-catalyzed reductive deprotection gives primary amines, which is an indirect alternative to the direct monoalkylation of ammonia.
- Martínez-Asencio, Ana,Ramón, Diego J.,Yus, Miguel
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scheme or table
p. 325 - 327
(2010/03/04)
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- Selective N-monoalkylation of aromatic amines with benzylic alcohols by a hydrogen autotransfer process catalyzed by unmodified magnetite
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A new catalyst for an old material: magnetite is a good catalyst for the selective N-alkylation of aromatic amines using benzylic alcohols as electrophiles. The process could be repeated up to eight times without losing effectiveness. The catalyst recycling is very easy, using a simple magnet. The catalyst is selective and could discriminate between aromatic and aliphatic amines, as well as between benzylic and aliphatic alcohols, as the reactions only take place with aromatic amines and benzylic alcohols.
- Martinez, Ricardo,Ramon, Diego J.,Yus, Miguel
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experimental part
p. 2176 - 2181
(2009/09/04)
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- Selective iridium-catalyzed alkylation of (hetero)aromatic amines and diamines with alcohols under mild reaction conditions
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A P,N-ligand-coordinated iridium complex has been employed as an efficient catalyst for the selective monoalkylation of (hetero) aromatic amines with alcohols. A significant improvement of this alkylation method has been achieved, such that it can be performed at a temperature of 70°C and with catalyst loadings as low as 0.1 mol% Ir, while still affording excellent yields of secondary amines. Furthermore, the high selectivity of this catalyst for the monoalkylation of aromatic amino functions has been successfully exploited for the alkylation of diamines in both symmetric and non-symmetric fashions, providing a novel and very efficient synthetic tool for the preparation of N,N'-dialkylated aromatic diamines.
- Blank, Benoit,Michlik, Stefan,Kempe, Rhett
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experimental part
p. 3790 - 3799
(2009/12/05)
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- 2-Pyridinyl β-ketones as new ligands for roomerature CuI-catalysed C-N coupling reactions
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2-Pyridinyl β-ketones were identified as new efficient ligands for CuI-catalysed N-arylation of aliphatic amines at room temperature with great selectivity and substrate scope tolerance.
- Wang, Deping,Ding, Ke
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supporting information; experimental part
p. 1891 - 1893
(2009/10/23)
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- An efficient method for the selective iridium-catalyzed monoalkylation of (hetero)aromatic amines with primary alcohols
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An efficient multi-gram scale synthesis protocol of a variety of P,N ligands is described. The synthesis is achieved in a two-step reaction. First, the amine is deprotonated and subsequently the chlorophosphine is added to yield the corresponding P,N ligand. Deprotonation of the amine is normally achieved with n-BuLi at low temperature, but for the preparation of ligands with a 2,2′-dipyridylamino backbone and phosphines with a high steric demand KH has to be employed in combination with reaction temperatures of 110°C for the salt metathesis step. The reaction of two equivalents of a selected P,N ligand with one equivalent of the iridium complex [IrCl(cod)]2 (cod=1,5-cyclooctadiene) affords P,N ligand-coordinated iridium complexes in quantitative yield. X-Ray single crystal structure analysis of one of these complexes reveals a monomeric five-coordinated structure in the solid state. The iridium complexes were used to form catalysts for the N-alkylation of aromatic amines with alcohols. The catalyst system was optimized by studying 8 different P,N ligands, 9 different solvents and 14 different bases. Systematic variation of the substrate to base and the amine to alcohol ratios as well as the catalyst loading led to optimized catalytic reaction conditions. The substrate scope of the developed catalytic protocol was shown by synthesizing 20 different amines of which 12 could be obtained in isolated yields higher than 90%. A new efficient catalyst system for the selective monoalkylation of primary aromatic and heteroaromatic amines with primary aromatic, heteroaromatic as well as aliphatic alcohols has been established. The reaction proceeds with rather moderate catalyst loadings.
- Blank, Benoit,Madalska, Martyna,Kempe, Rhett
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supporting information; experimental part
p. 749 - 758
(2009/04/10)
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- Synthesis of nitro N,N′-dipyridinylamines via oxidative nucleophilic substitution of hydrogen
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The amination of 3-nitropyridines with aromatic amides generated from various aminopyridine derivatives proceeded unexpectedly in the position para to the nitro group, giving the oxidative nucleophilic substitution of hydrogen (ONSH) derived compounds. After optimization, this reaction allowed easy access to interesting 3-nitro-substituted N,N′-dipyridinylamines. Georg Thieme Verlag Stuttgart.
- Patriciu, Oana-Irina,Pillard, Christelle,Finaru, Adriana-Luminita,Sandulescu, Ioan,Guillaumet, Gerald
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p. 3868 - 3876
(2008/09/17)
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- Reductive amination of carbonyl compounds using NaBH4 in a Br?nsted acidic ionic liquid
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Reductive amination of carbonyl compounds using sodium borohydride is conducted in the Br?nsted acidic ionic liquid, 1-methyl imidazolium tetrafluoroborate ([HMIm][BF4]). The ionic liquid plays the dual role of solvent as well as catalyst for efficient conversion of aldehydes and ketones to amines in excellent yields without the formation of side products.
- Reddy, P. Srinivasa,Kanjilal, Sanjit,Sunitha,Prasad, Rachapudi B.N.
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p. 8807 - 8810
(2008/03/18)
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- Synthesis and microbiological evaluations of (N-heteroaryl)arylmethanamines and their Schiff bases
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The synthesis as well as the antimicrobial and antiviral activities of new (N-heteroaryl)arylmethanamines and their Schiff bases are reported. None of the tested compounds showed activity against Herpes simplex virus type 2 and against Gram positive and Gram negative bacteria. Weak or moderate activity on poliovirus Sabin type 1, on reverse transcriptase and against Cryptococcus neoformans was shown by some of the tested compounds. Viceversa several synthesized compounds exhibited a moderate or good activity against strains of Candida albicans, while only some of the tested compounds were found moderately active against strains of Candida sp. Instead numerous new compounds 3 or 4 were active as control against isolates of plant pathogenic fungi. The obtained results are discussed on the basis of structure-activity relationships.
- Fioravanti,Biava,Donnarumma,Porretta,Simonetti,Villa,Porta-Puglia,Deidda,Maullu,Pompei
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p. 643 - 652
(2007/10/03)
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