- Enhanced Hydride Donation Achieved Molybdenum Catalyzed Direct N-Alkylation of Anilines or Nitroarenes with Alcohols: From Computational Design to Experiment
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An example of homogeneous Mo-catalyzed direct N-alkylation of anilines or nitroarenes with alcohols is presented. The DFT aimed design suggested the easily accessible bis-NHC-Mo(0) complex features a strong hydride-donating ability, achieving effective N-alkylation of anilines or challenging nitroarenes with alcohols. The enhanced hydride-donating strategy should be useful in designing highly active systems for borrowing hydrogen transformations.
- Huang, Ming,Huang, Yong-Liang,Ke, Zhuofeng,Lan, Xiao-Bing,Li, Weikang,Liu, Jiahao,Liu, Yan,Ye, Zongren,Zhao, Cunyuan
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p. 10377 - 10382
(2021/08/31)
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- Mimicking transition metals in borrowing hydrogen from alcohols
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Borrowing hydrogen from alcohols, storing it on a catalyst and subsequent transfer of the hydrogen from the catalyst to anin situgenerated imine is the hallmark of a transition metal mediated catalyticN-alkylation of amines. However, such a borrowing hydrogen mechanism with a transition metal free catalytic system which stores hydrogen molecules in the catalyst backbone is yet to be established. Herein, we demonstrate that a phenalenyl ligand can imitate the role of transition metals in storing and transferring hydrogen molecules leading to borrowing hydrogen mediated alkylation of anilines by alcohols including a wide range of substrate scope. A close inspection of the mechanistic pathway by characterizing several intermediates through various spectroscopic techniques, deuterium labelling experiments, and DFT study concluded that the phenalenyl radical based backbone sequentially adds H+, H˙ and an electron through a dearomatization process which are subsequently used as reducing equivalents to the C-N double bond in a catalytic fashion.
- Banik, Ananya,Ahmed, Jasimuddin,Sil, Swagata,Mandal, Swadhin K.
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p. 8353 - 8361
(2021/07/02)
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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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- Switchable Imine and Amine Synthesis Catalyzed by a Well-Defined Cobalt Complex
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Switchable imine and amine synthesis catalyzed by a tripodal ligand-supported well-defined cobalt complex is presented herein. A large variety of primary alcohols and amines were selectively converted to imines or amines in good to excellent yields. It is discovered that the base plays a crucial role on the selectivity. A catalytic amount of base leads to the imine formation, while an excess loading of base results in the amine product. This strategy on product selectivity also strongly depends on the organometallic catalysts in use. We expect that the present study could provide useful insights toward selective organic synthesis and catalyst design.
- Paudel, Keshav,Xu, Shi,Hietsoi, Oleksandr,Pandey, Bedraj,Onuh, Chuka,Ding, Keying
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supporting information
p. 418 - 426
(2021/02/01)
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- Direct electrochemical reductive amination between aldehydes and amines with a H/D-donor solvent
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A novel electrochemical synthesis protocol has been achieved for reductive amination between aldehydes and amines in undivided cells at room temperature. Under metal-free and external-reductant-free electrolysis conditions, various important secondary amine products are obtained in moderate-to-high yields. Deuterium-labeling experiments have demonstrated that low-toxicity DMSO acts both as a solvent and a H-donor in the reaction. On this basis, various deuterium-labeled products with good-to-excellent D-incorporation have been synthesized by using DMSO-d6 as a solvent. Furthermore, a molecule with GR-antagonistic activity has been synthesized through further sulfonylation.
- Chen, Lu,Hong, Huanliang,Hu, Jinhui,Huang, Yubing,Li, Yibiao,Liang, Gen,Pu, Suyun,Zhu, Zhongzhi,Zou, Zirong
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supporting information
p. 5832 - 5837
(2020/11/03)
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- Simple electrochemical reduction of nitrones to amines
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The use of electricity allows the reduction of nitrones containing aromatic and heteroaromatic rings to the corresponding amines. The main advantage of this protocol relies on the fact that only electrons are needed, avoiding the use of different chemical
- Rodrigo, Eduardo,Waldvogel, Siegfried R.
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p. 2044 - 2047
(2019/02/20)
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- Ruthenium(II)-(Arene)-N-Heterocyclic Carbene Complexes: Efficient and Selective Catalysts for the N-Alkylation of Aromatic Amines with Alcohols
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A series of unsymmetrical 1,3-disubstituted benzimidazolium chlorides were synthesized as N-heterocyclic carbene (NHC) precursors. These compounds were used for synthesis of the new ruthenium(II) complexes of the type [RuCl2(arene)(NHC)], (arene = η6-p-cymene). The structures of all compounds were characterized by 1H NMR, 13C NMR and FT-IR spectroscopy techniques. The catalytic activity of the ruthenium complexes has been evaluated with respect to the mono-N-alkylation reactions of aromatic amines with various alcohol derivatives under solvent-free conditions at 120 °C using the borrowing hydrogen strategy.
- Kalo?lu, Nazan,Achard, Mathieu,Bruneau, Christian,?zdemir, ?smail
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supporting information
p. 2598 - 2606
(2019/06/14)
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- Alcohol Amination Catalyzed by Copper Powder as a Self-Supported Catalyst
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Catalytic alcohol amination is a sustainable reaction for N-alkyl amine synthesis. Homogeneous and supported copper catalysts have long been studied for this reaction and have given some impressive results. In this study, copper powder is found to behave as an active catalyst for alcohol amination, giving better catalytic performance than metal-oxide-supported nanocopper catalysts. Catalyst characterization suggests that the copper powder can be considered as a self-supported nanocopper catalyst (i.e., nanocopper supported on copper particles). These results might promote the study of unsupported transition metal powders in sustainable catalytic reactions.
- Wu, Yajuan,Huang, Yongji,Dai, Xingchao,Shi, Feng
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p. 3185 - 3191
(2018/11/30)
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- Cobalt-Rhodium Heterobimetallic Nanoparticle-Catalyzed N-Alkylation of Amines with Alcohols to Secondary and Tertiary Amines
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Without the requirement for base or other additives, Co2Rh2/C can selectively catalyze both mono- and bis-N-alkylation through the coupling of simple alcohols with amines, yielding a range of secondary and tertiary amines in good to excellent isolated yields. The reaction can be applied to benzyl alcohol with optically active 1-phenylethan-1-amines, and secondary amines were isolated in quantitative yields with an excellent enantiomeric excess (ee > 94%). Selectivity is achieved by varying the reaction temperature and amount of catalyst used. This catalytic system has several advantages including eco-friendliness and a simple workup procedure. The catalyst can be successfully recovered and reused ten times without any significant loss of activity.
- Chung, Hyunho,Chung, Young Keun
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p. 8533 - 8542
(2018/07/30)
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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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- Benzimidazolium sulfonate ligand precursors and application in ruthenium-catalyzed aromatic amine alkylation with alcohols
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New benzimidazolium sulfonate salts have been prepared and fully characterized. They have been associated in situ with [RuCl2(p-cymene)]2 to generate efficient catalytic systems operating at 120 °C under neat conditions in the presence of potassium tert-butylate for selective N-alkylation of primary aromatic amines into secondary amines.
- Kaloglu, Nazan,?zdemir, Ismail,Gürbüz, Nevin,Achard, Mathieu,Bruneau, Christian
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- General and selective reductive amination of carbonyl compounds using a core-shell structured Co3O4/NGr@C catalyst
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The application of heterogenized non-noble metal-based catalysts in selective catalytic hydrogenation processes is still challenging. In this respect, the preparation of a well-defined cobalt-based catalyst was investigated by immobilization of the corresponding cobalt(ii)-phenanthroline-chelate on Vulcan XC72R carbon powder. The formed core-shell structured cobalt/cobalt oxide nanocomposites are encapsulated by nitrogen-enriched graphene layers. This promising cheap heterogeneous catalyst allows for an efficient domino reductive amination of carbonyl compounds with nitroarenes. This journal is
- Stemmler, Tobias,Westerhaus, Felix A.,Surkus, Annette-Enrica,Pohl, Marga-Martina,Junge, Kathrin,Beller, Matthias
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p. 4535 - 4540
(2014/12/10)
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- Organic ligand-free alkylation of amines, carboxamides, sulfonamides, and ketones by using alcohols catalyzed by heterogeneous Ag/Mo oxides
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Complicated and expensive organic ligands are normally essential in fine chemical synthesis at preparative or industrial levels. The synthesis of fine chemicals by using heterogeneous catalyst systems without additive organic ligand is highly desirable but severely limited due to their poor generality and rigorous reaction conditions. Here, we show the results of carbon-nitrogen or carbon-carbon bond formation catalyzed by an Ag/Mo hybrid material with specific Ag6Mo10O33 crystal structure. 48 nitrogen- or oxygen-containing compounds, that is, amines, carboxamides, sulfonamides, and ketones, were successfully synthesized through a borrowing-hydrogen mechanism. Up to 99% isolated yields were obtained under relatively mild conditions without additive organic ligand. The catalytic process shows promise for the efficient and economic synthesis of amine, carboxamide, sulfonamide, and ketone derivatives because of the simplicity of the system and ease of operation. Copyright
- Cui, Xinjiang,Zhang, Yan,Shi, Feng,Deng, Youquan
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supporting information; experimental part
p. 1021 - 1028
(2011/03/20)
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- TRICHLOROSILANE-IMINE COMPLEXES. A NEW METHOD FOR THE REDUCTION OF IMINES TO AMINES
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It has been found that trichlorosilane adds regio-specifically to the carbon-nitrogen double bond of imines under mild conditions to yield hydrolytically unstable N-trichlorosilyl intermediates.The latter can be hydrolyzed in situ by alcoholic base to give the corresponding amines in moderate to good yields.Variously substituted aldo and keto imines, both alkyl and aryl, were tested to demonstrate the scope of the reaction.The facility of trichlorosilane addition appears to depend on the nature of the groups directly attached to the carbon-nitrogen double bond.Hydride trapping experiments suggest an intramolecular rather than intermolecular hydride transfer during the course of the reaction.
- Benkeser, Robert A.,Snyder, Dudley C.
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p. 107 - 115
(2007/10/02)
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