- Reusable Co-nanoparticles for general and selectiveN-alkylation of amines and ammonia with alcohols
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A general cobalt-catalyzedN-alkylation of amines with alcohols by borrowing hydrogen methodology to prepare different kinds of amines is reported. The optimal catalyst for this transformation is prepared by pyrolysis of a specific templated material, which is generatedin situby mixing cobalt salts, nitrogen ligands and colloidal silica, and subsequent removal of silica. Applying this novel Co-nanoparticle-based material, >100 primary, secondary, and tertiary amines includingN-methylamines and selected drug molecules were conveniently prepared starting from inexpensive and easily accessible alcohols and amines or ammonia.
- Beller, Matthias,Gawande, Manoj B.,Jagadeesh, Rajenahally V.,Kadam, Ravishankar G.,Li, Xinmin,Ma, Zhuang,Petr, Martin,Zbo?il, Radek,Zhou, Bei
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p. 111 - 117
(2022/01/06)
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- Hydrosilylation and Mukaiyama aldol-type reaction of quinolines and hydrosilylation of imines catalyzed by a mesoionic carbene-stabilized borenium ion
-
Aldimines and ketimines containing electron-donating and electron-withdrawing groups can be hydrosilylated with borenium catalysts at as low as 1 mol% catalyst loading at room temperature, providing the corresponding secondary amines in excellent yields. Reactions with 2-phenylquinoline gave the 1,4-hydrosilylquinoline product selectively which can be further functionalized in a one-pot synthesis to give unique γ-amino alcohol derivatives. Control experiments suggest that the borenium ion catalyzes both the hydrosilylation and subsequent addition to the aldehyde.
- Bestvater, Brian P.,Clarke, Joshua J.,Crudden, Cathleen M.,DeJesus, Joseph F.,Devaraj, Karthik,Eisenberger, Patrick,Kojima, Ryoto
-
supporting information
p. 6786 - 6791
(2021/08/20)
-
- Synthesis ofN-aryl amines enabled by photocatalytic dehydrogenation
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Catalytic dehydrogenation (CD)viavisible-light photoredox catalysis provides an efficient route for the synthesis of aromatic compounds. However, access toN-aryl amines, which are widely utilized synthetic moieties,viavisible-light-induced CD remains a significant challenge, because of the difficulty in controlling the reactivity of amines under photocatalytic conditions. Here, the visible-light-induced photocatalytic synthesis ofN-aryl amines was achieved by the CD of allylic amines. The unusual strategy using C6F5I as an hydrogen-atom acceptor enables the mild and controlled CD of amines bearing various functional groups and activated C-H bonds, suppressing side-reaction of the reactiveN-aryl amine products. Thorough mechanistic studies suggest the involvement of single-electron and hydrogen-atom transfers in a well-defined order to provide a synergistic effect in the control of the reactivity. Notably, the back-electron transfer process prevents the desired product from further reacting under oxidative conditions.
- Kim, Jungwon,Kim, Siin,Choi, Geunho,Lee, Geun Seok,Kim, Donghyeok,Choi, Jungkweon,Ihee, Hyotcherl,Hong, Soon Hyeok
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p. 1915 - 1923
(2021/02/22)
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- Iron-catalysed hydroboration of non-activated imines and nitriles: Kinetic and mechanistic studies
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Iron-catalysed hydroboration of imines and nitriles has been developed under low catalyst loading (1 mol%) in the presence of HBpin. A wide scope of substrate was found to smoothly undergo hydroboration, including electron releasing/withdrawing and haloge
- Bazkiaei, Adineh Rezaei,Wiseman, Michael,Findlater, Michael
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p. 15284 - 15289
(2021/05/19)
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- Cooperative catalysis of molybdenum with organocatalysts for distribution of products between amines and imines
-
Multi-amino groups and nitrogen donors compound was discovered as an organocatalyst for N-alkylation of alcohols with amines in the presence of Mo(CO)6. The Mo(CO)6/organocatalyst binary system has shown to be a highly active catalyst for the N-alkylation reaction between alcohols and amines with excellent tolerance of variable starting materials bearing different functional groups. Of particular note, this method possessing a superiority selectivity in the synthesis of N-alkylated amines or imines, which can be controlled by the reaction temperature. The cooperative catalysis mechanism in combination of Mo(CO)6 with organocatalyst was elucidated by control experiments.
- Wu, Di,Bu, Qingqing,Guo, Cheng,Dai, Bin,Liu, Ning
-
-
- Synthesis of NHC-Iridium(III) Complexes Based on N-Iminoimidazolium Ylides and Their Use for the Amine Alkylation by Borrowing Hydrogen Catalysis
-
Anionic NHC ligands recently developed in our group, derived from N-iminoimidazolium ylides, were used to synthesize NHC-iridium(III) complexes. Their catalytic activities were evaluated in the amine alkylation of anilines using borrowing hydrogen catalysis. The high-yielding synthesis of a small library of complexes allowed a rapid screening of the ideal steric bulk of the NHC unit and basicity of the anionic tether for the investigated model reaction. A bulky aromatic N group on the imidazolidene moiety is required to achieve high catalytic activity, and the latter is proportional to the basicity of the anionic group. A selected substrate scope of the reaction was performed, providing fair to excellent yields of the desired alkylated anilines.
- Guérin, Vincent,Legault, Claude Y.
-
supporting information
p. 408 - 417
(2021/02/01)
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- BF3·Et2O as a metal-free catalyst for direct reductive amination of aldehydes with amines using formic acid as a reductant
-
A versatile metal- and base-free direct reductive amination of aldehydes with amines using formic acid as a reductant under the catalysis of inexpensive BF3·Et2O has been developed. A wide range of primary and secondary amines and diversely substituted aldehydes are compatible with this transformation, allowing facile access to various secondary and tertiary amines in high yields with wide functional group tolerance. Moreover, the method is convenient for the late-stage functionalization of bioactive compounds and preparation of commercialized drug molecules and biologically relevant N-heterocycles. The procedure has the advantages of simple operation and workup and easy scale-up, and does not require dry conditions, an inert atmosphere or a water scavenger. Mechanistic studies reveal the involvement of imine activation by BF3and hydride transfer from formic acid.
- Fan, Qing-Hua,Liu, Xintong,Luo, Zhenli,Pan, Yixiao,Xu, Lijin,Yang, Ji,Yao, Zhen,Zhang, Xin
-
supporting information
p. 5205 - 5211
(2021/07/29)
-
- Direct N-Alkylation/Fluoroalkylation of Amines Using Carboxylic Acids via Transition-Metal-Free Catalysis
-
A scalable protocol of direct N-mono/di-alkyl/fluoroalkylation of primary/secondary amines has been constructed with various carboxylic acids as coupling agents under the catalysis of a simple air-tolerant inorganic salt, K3PO4. Advantageous features include 100 examples, 10 drugs and drug-like amines, fluorinated complex tertiary amines, gram-scale synthesis and isotope-labelling amine, thus demonstrating the potential applicability in industry of this methodology. The involvement of relatively less reactive silicon-hydride compared with the traditional reactive metal-hydride or boron-hydride species required to reduce the amide intermediates presumably contributes to the remarkable functional group compatibility. (Figure presented.).
- Lu, Chunlei,Qiu, Zetian,Xuan, Maojie,Huang, Yan,Lou, Yongjia,Zhu, Yiling,Shen, Hao,Lin, Bo-Lin
-
supporting information
p. 4151 - 4158
(2020/08/21)
-
- Cross dehydrogenative coupling strategy for allylation of benzylanilines promoted by DDQ
-
A cross dehydrogenative coupling strategy for allylation of benzylanilines promoted by DDQ is reported, which uses nonmetallic quinone DDQ as an oxidant in the allylation of N-benzylanilines under mild conditions. C–C bond with high selectivity and activity was constructed in this reaction and homoallylic amines were obtained with yields of up to 99%.
- Xiong, Ruimei,Hussain, Muhammad Ijaz,Liu, Qing,Xia, Wen,Xiong, Yan
-
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- Synthesis and characterization of N,N-chelate manganese complexes and applications in C[sbnd]N coupling reactions
-
Bidentate NN-ligands have been derived from the reaction between aldehydes and 2-(aminomethyl)pyridine. The treatment of these ligands with Mn(CO)5Br gave complexes that are highly bench stable. The complexes were characterized by various analytical and spectral methods. Single-crystal XRD of complex Mn-2 was performed, which indicates an octahedral geometry around the metal center. The complexes efficiently catalyze the N-alkylation of anilines with alcohols under optimized reaction conditions.
- Das, Kuhali,Kumar, Amol,Jana, Akash,Maji, Biplab
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supporting information
(2019/12/28)
-
- Quantitative NaH catalytic hydroboration of aldimines
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The catalytic hydroboration of aldimines was demonstrated, with only 3 mol% NaH required for the quantitative production of secondary amines under minimal solvent conditions. In addition, chemoselective hydroboration in the presence of other reducible functional groups was achieved. DFT calculations were then used to propose a reaction mechanism for imine hydroboration. This journal is
- An, Duk Keun,Hwang, Hyonseok,Kim, Hanbi,Lee, Ji Hye
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p. 11330 - 11335
(2020/07/15)
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- Lithium bromide: an inexpensive and efficient catalyst for imine hydroboration with pinacolborane at room temperature
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An efficient protocol for the hydroboration of imines is reported. Lithium halide salts are effective catalysts to convert aldimines and ketimines to their corresponding amines. Here, we report excellent isolated yield of secondary amines (>95%) using 3 mol% lithium bromide in THF at room temperature. In addition, DFT calculations for a plausible reaction pathway are reported.
- An, Duk Keun,Hwang, Hyonseok,Kim, Hanbi,Kim, Hyun Tae,Lee, Ji Hye
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p. 34421 - 34427
(2020/10/12)
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- Chemoselective Reductive Aminations in Aqueous Nanoreactors Using Parts per Million Level Pd/C Catalysis
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Condensation in recyclable water between aldehydes or ketones and amines occurs smoothly within the hydrophobic cores of nanomicelles, resulting in imine formation that is subject to subsequent reduction leading, overall, to reductive amination. This micellar technology enables the synthesis of several types of pharmaceuticals, a new procedure that relies on only 2000 ppm (0.20 mol %) palladium from commercially available Pd/C. A broad range of substrates can be used under mild conditions, leading to high chemical yields of the desired secondary and tertiary amines.
- Casotti, Gianluca,Gao, Eugene S.,Jin, Henry S.,Lipshutz, Bruce H.,Takale, Balaram S.,Thakore, Ruchita R.
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supporting information
(2020/09/09)
-
- Selective Synthesis of Secondary Amines from Nitriles by a User-Friendly Cobalt Catalyst
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Selective hydrogenation/reductive amination of nitriles to secondary amines catalyzed by an inexpensive and user-friendly cobalt complex, (Xantphos)CoCl2, is reported. The use of (Xantphos)CoCl2 and ammonia borane (NH3?BH3) combination affords the selective reduction of nitriles to symmetrical secondary amines, whereas the employment of (Xantphos)CoCl2 and dimethylamine borane (Me2NH?BH3) along with external amines produce unsymmetrical secondary amines and tertiary amines. The general applicability of this methodology is demonstrated by the synthesis of 43 symmetrical and unsymmetrical secondary and tertiary amines bearing diverse functionalities. (Figure presented.).
- Sharma, Dipesh M.,Punji, Benudhar
-
supporting information
p. 3930 - 3936
(2019/07/12)
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- Unlocking the catalytic potential of tris(3,4,5-trifluorophenyl)borane with microwave irradiation
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The catalytic activity of tris(3,4,5-trifluorophenyl)borane has been explored in the 1,2-hydroboration reactions of unsaturated substrates. Under conventional conditions, the borane was found to be active only in the hydroboration of aldehyde, ketone and imine substrates, with alkenes and alkynes not being reduced effectively. The use of microwave irradiation on the other hand has permitted alkenes and alkynes to be hydroborated in good yields.
- Carden, Jamie L.,Gierlichs, Lukas J.,Wass, Duncan F.,Browne, Duncan L.,Melen, Rebecca L.
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supporting information
p. 318 - 321
(2019/01/09)
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- H2 Activation by Non-Transition-Metal Systems: Hydrogenation of Aldimines and Ketimines with LiN(SiMe3)2
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In recent years, H2 activation at non-transition-metal centers has met with increasing attention. Here, a system in which H2 is activated and transferred to aldimines and ketimines using substoichiometric amounts of lithium bis(trimethylsilyl)amide is reported. Notably, the reaction tolerates the presence of acidic protons in the α-position. Mechanistic investigations indicated that the reaction proceeds via a lithium hydride intermediate as the actual reductant.
- Elliott, Daniel C.,Marti, Alex,Mauleón, Pablo,Pfaltz, Andreas
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p. 1918 - 1922
(2019/01/16)
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- A Biphasic Medium Slows Down the Transfer Hydrogenation and Allows a Selective Catalytic Deuterium Labeling of Amines from Imines Mediated by a Ru?H/D+ Exchange in D2O
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The transfer hydrogenation (TH) of several aldimines has been studied using [RuCl(p-cymene)(dmbpy)]BF4, 1, (dmbpy=4,4′-dimethyl-2,2′-bipyridine) as a precatalyst. Both neat water and a biphasic water/toluene mixture (w/t) have been successfully used as solvents. In the w/t medium the corresponding precursors, amine and aldehyde, were also used as substrates for a transfer hydrogenative reductive amination. Selective deuterium labeling of the resulting alkylated amines was the main goal of this work. On using D2O the D-content in the amine was negligible but a high level of D-incorporation was achieved in D2O/toluene. According to calculations, this is due to the effect of the relative rates of the hydride transfer and that of the RuH/D+ exchange. The incorporation of deuterium increases with time as a consequence of the reduction in the hydride transfer rate as the substrate concentration diminishes. The recyclability assays performed reflect the importance of pH in the selectivity of the TH towards the imine or the aldehyde resulting from imine hydrolysis.
- Ruiz-Casta?eda, Margarita,Carrión, M. Carmen,Santos, Lucía,Manzano, Blanca R.,Espino, Gustavo,Jalón, Félix A.
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p. 5541 - 5550
(2018/12/11)
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- Cross-dehydrogenative coupling strategy for phosphonation and cyanation of secondary N-alkyl anilines by employing 2,3-dichloro-5,6-dicyanobenzoquinone
-
The cross-dehydrogenative coupling strategy for metal-free phosphonation and cyanation of secondary N-alkyl anilines has been developed firstly under mild reaction conditions. Based on detailed optimization of reaction conditions, the substrate generality of N-alkyl anilines and various hydrogen phosphonates has been investigated, and a series of versatile α-aminophosphonates and α-aminonitriles were therefore furnished in good to excellent yields. A plausible collective reaction mechanism through dehydrogenation to imine formation, then to respective α-aminophosphonates and α-aminonitriles was proposed.
- Liu, Qing,Yu, Shuchen,Hu, Liangzhen,Hussain, Muhamad Ijaz,Zhang, Xiaohui,Xiong, Yan
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p. 7209 - 7217
(2018/11/10)
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- BINAP-copper supported by hydrotalcite as an efficient catalyst for the borrowing hydrogen reaction and dehydrogenation cyclization under water or solvent-free conditions
-
A BINAP-Cu system supported by hydrotalcite has been developed and proved to be a highly efficient catalyst for the atom-efficient and green borrowing hydrogen reaction and dehydrogenative cyclization. This BINAP-Cu complex supported by hydrotalcite is highly air-stable and can be recycled at least five times under solvent-free conditions. Notably, 1-benzyl-2-aryl-1H-benzo[d]imidazole derivatives could be synthesized from alcohols in only one step with water as the solvent for the first time. This provided a much greener and efficient catalytic method towards the synthesis of functionalized amines, ketones and 1-benzyl-2-aryl-1H-benzo[d]imidazole derivatives with high yields under water or solvent-free conditions.
- Xu, Zhaojun,Yu, Xiaoli,Sang, Xinxin,Wang, Dawei
-
supporting information
p. 2571 - 2577
(2018/06/11)
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- C-N Bond Formation Catalyzed by Ruthenium Nanoparticles Supported on N-Doped Carbon via Acceptorless Dehydrogenation to Secondary Amines, Imines, Benzimidazoles and Quinoxalines
-
Ruthenium nanoparticles (NPs) supported on N-doped carbon (Ru/N?C) were prepared by the pyrolysis of cis-Ru(phen)2Cl2 loaded onto carbon powder (VULCAN XC72R) at 800 °C. Ru/N?C NPs (0.2 mol% Ru) selectively catalyzed either acceptorless dehydrogenation coupling (ADC) or auto-transfer-hydrogen (ATH) reactions of amines with alcohols to imines and secondary amines. Such selectivity could be controlled by the choice of alkali metal ion associated with the base. Under similar catalytic conditions, the ADC cross-coupling of diamines with primary alcohols or diols afforded the corresponding benzimidazoles and quinoxalines in good to excellent yields. This catalytic system displayed good activity, recyclability, and wide applicability to a diverse range of substrates.
- Guo, Bin,Li, Hong-Xi,Zhang, Shi-Qi,Young, David James,Lang, Jian-Ping
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p. 5627 - 5636
(2018/12/04)
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- Iridium(III)- benzoxazolyl and benzothiazolyl phosphine ligands catalyzed versatile alkylation reactions with alcohols and the synthesis of quinolines and indole
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A series of benzoxazolyl and benzothiazolyl phosphine ligands 4a-4g were synthesized and characterized, which prepared from commercially available 2-aminophenol/2-aminobenzenethiol and 2-bromobenzaldehyde via cyclization and phosphination. The representative ligands 4c and 4e were determined by single-crystal X-ray diffraction. The corresponding iridium complexes could be generated in situ when [Cp*IrCl2]2 (Cp* = pentamethylcyclopentadienyl) encountered ligands. The molecular structures of complexes 5c and 5e were crystallographically characterized. The dihedral angles of N (1)-C (1)-C (8)-C (9) showed an increasing twist compared with the corresponding ligand. The iridium (III) catalysts were screened, [Cp*IrCl2]2/4a proved to be the optimal catalyst, which exhibited efficient catalytic activity toward versatile alkylations including ketones, secondary alcohols and amines with primary alcohols. Additionally, the synthesis of quinolines from ketones with 2-aminobenzyl alcohol by intermolecular cyclization and indole from 2-(2-aminophenyl)ethanol by intramolecular cyclization were achieved under the optimized conditions.
- Huang, Shuang,Wu, Si-Peng,Zhou, Quan,Cui, He-Zhen,Hong, Xi,Lin, Yue-Jian,Hou, Xiu-Feng
-
-
- Main-Group-Catalyzed Reductive Alkylation of Multiply Substituted Amines with Aldehydes Using H2
-
Given the growing demand for green and sustainable chemical processes, the catalytic reductive alkylation of amines with main-group catalysts of low toxicity and molecular hydrogen as the reductant would be an ideal method to functionalize amines. However, such a process remains challenging. Herein, a novel reductive alkylation system using H2 is presented, which proceeds via a tandem reaction that involves the B(2,6-Cl2C6H3)(p-HC6F4)2-catalyzed formation of an imine and the subsequent hydrogenation of this imine catalyzed by a frustrated Lewis pair (FLP). This reductive alkylation reaction generates H2O as the sole byproduct and directly functionalizes amines that bear a remarkably wide range of substituents including carboxyl, hydroxyl, additional amino, primary amide, and primary sulfonamide groups. The synthesis of isoindolinones and aminophthalic anhydrides has also been achieved by a one-pot process that consists of a combination of the present reductive alkylation with an intramolecular amidation and intramolecular dehydration reactions, respectively. The reaction showed a zeroth-order and a first-order dependence on the concentration of an imine intermediate and B(2,6-Cl2C6H3)(p-HC6F4)2, respectively. In addition, the reaction progress was significantly affected by the concentration of H2. These results suggest a possible mechanism in which the heterolysis of H2 is facilitated by the FLP comprising THF and B(2,6-Cl2C6H3)(p-HC6F4)2.
- Hoshimoto, Yoichi,Kinoshita, Takuya,Hazra, Sunit,Ohashi, Masato,Ogoshi, Sensuke
-
supporting information
p. 7292 - 7300
(2018/06/01)
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- Conversion of aldimines to secondary amines using iron-catalysed hydrosilylation
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Iron-catalyzed hydrosilylation of imines to amines using a well-defined iron complex is reported. This method employs relatively mild conditions, by reaction of imine, (EtO)3SiH in a 1 : 2 ratio in the presence of 1 mol% precatalyst ([BIAN]Fe(η6-toluene), 3, BIAN = bis(2,6-diisopropylaniline)acenaphthene) at 70 °C. A broad scope of imines was readily converted into the corresponding secondary amines without the need for precatalyst activators.
- Saini, Anu,Smith, Cecilia R.,Wekesa, Francis S.,Helms, Amanda K.,Findlater, Michael
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p. 9368 - 9372
(2019/01/03)
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- One-pot reductive amination of carbonyl compounds with nitro compounds with CO/H2O as the hydrogen donor over non-noble cobalt catalyst
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The one-pot reductive amination of carbonyl compounds with nitro compounds over heterogeneous non-noble metal catalysts was developed for the first time by transfer hydrogenation with CO/H2O as the hydrogen donor. Nitrogen-doped carbon supported cobalt nanoparticles were observed to be active toward this reaction, affording structurally-diverse secondary amines with high yields. Kinetic studies revealed that the transfer hydrogenation of imines (C[dbnd]N bonds) was the rate-determining step. Reaction mechanism studies indicated that both nitrogen and cobalt nanoparticles were important for the transfer hydrogenation with CO/H2O to generate the proton (N[sbnd]H+) and hydride (Co[sbnd]H?) as the active species. Furthermore, the heterogeneous cobalt catalyst was highly stable without the loss of its catalytic activity during the recycling experiments.
- Zhou, Peng,Yu, Changlin,Jiang, Liang,Lv, Kangle,Zhang, Zehui
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p. 264 - 273
(2017/06/23)
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- An Efficient Homogenized Ruthenium(II) Pincer Complex for N-Monoalkylation of Amines with Alcohols
-
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)
-
- Hemilabile N-heterocyclic carbene (NHC)-nitrogen-phosphine mediated Ru (II)-catalyzed N-alkylation of aromatic amine with alcohol efficiently
-
Based on the hemilability, a novel N-heterocyclic carbene (NHC)-nitrogen-phosphine ligand (1) was synthesized, and the combination of it with [Ru(COD)Cl2]n showed the high activity and selectivity with a low Ru loading of 0.1% for the N-alkylation of amine with alcohol. Especially, for these substrates with pyridine backbone, even if the catalyst loading was as low as 0.01%, good yields (81–95%) of the desired products were achieved.
- Yu, Xiao-Jun,He, Hai-Yu,Yang, Lei,Fu, Hai-Yan,Zheng, Xue-Li,Chen, Hua,Li, Rui-Xiang
-
-
- Ligand-free and non-solvent synthesis method for preparing secondary amine under catalysis of ruthenium trichloride
-
The invention discloses a ligand-free and non-solvent synthesis method for preparing secondary amine under catalysis of ruthenium trichloride. The method comprises steps as follows: reactants including nitrobenzene compounds, alcohol compounds, an alkaline compound, ruthenium trichloride and glycerin in the mole ratio being 1:(1-2):(1-2):(0.02-0.05):(5-15) are added to a reaction container provided with a stirring device under the protection of inert gases, the mixture is stirred at the temperature of 100-150 DEG C and reacts for 20-30 hours, and secondary amine compounds are obtained. RuCl3 is directly used as a catalyst under the condition that no auxiliary ligand or solvent is added, toxic phosphine-containing ligands are avoided, and consumption of alcohol is reduced to a great extent. Besides, according to the method, secondary amine is selectively generated by adding glycerin serving as a hydrogen source, the whole process is environment-friendly, efficient and easy to operate, and the ligand-free and non-solvent synthesis method is a good method for synthesis of secondary amine.
- -
-
Paragraph 0051; 0052; 0053; 0054
(2016/10/10)
-
- Phosphine ligand-free RuCl3-catalyzed reductive N-alkylation of aryl nitro compounds
-
Without using any additional ligands, RuCl3efficiently catalyses the reductive N-alkylation of aryl nitro compounds with alcohols using bio-based glycerol as the hydrogen source and without the need for any added solvents. The reaction can be easily manipulated to produce either imines or secondary amines in high yields. RuCl3-catalyzed reductive N-alkylation of nitroarenes with alcohols affords the corresponding imine products in good to excellent yields. Under the same reaction conditions, the one-pot sequential reaction of nitroarenes with alcohols and glycerol also gives amines in higher yields.
- Tan, Da-Wei,Li, Hong-Xi,Young, David James,Lang, Jian-Ping
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p. 4169 - 4176
(2016/07/06)
-
- Palladium nanoparticles stabilised by cinchona-based alkaloids in glycerol: Efficient catalysts for surface assisted processes
-
Palladium nanoparticles (PdNPs) were synthesised and fully characterised, both in solution and the solid state, using naturally-occurring cinchona-based alkaloids in neat glycerol. These nano-systems were stable under reaction conditions, finding applications in hydrogenation and hydrodehalogenation processes, as a result of their surface-like behaviour. Their reactivity was improved in relation to that involving PdNPs stabilised by phosphines and also by Pd/C as a heterogenous catalyst, mainly in terms of recyclability. In particular, the colloidal palladium catalyst stabilised by quinidine was highly efficient to promote the hydrodechlorination of aromatic compounds under low dihydrogen pressure. These original catalysts found applications in the synthesis of secondary and tertiary amines including N-substituted anilines, by means of one-pot tandem Pd-catalysed methodologies under smooth conditions. In all of these processes, glycerol performed a crucial function as a liquid support for the immobilisation of nanoparticle-based catalysts, allowing both the stabilisation of the nano-catalysts and easy recycling of the catalytic phase.
- Reina,Pradel,Martin,Teuma,Gómez
-
p. 93205 - 93216
(2016/10/11)
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- Esters, Including Triglycerides, and Hydrogen as Feedstocks for the Ruthenium-Catalyzed Direct N-Alkylation of Amines
-
Triglycerides are used for the direct N-alkylation of amines with molecular hydrogen for the first time. A broad range of interesting and industrially relevant secondary and tertiary amines are obtained in the presence of an in situ formed Ru/Triphos complex. Notably, plant oil can be efficiently applied in this single-step process. Moreover, a variety of other methyl esters can be used as N-alkylation agents in the presence of hydrogen for the synthesis of more advanced building blocks.
- Adam, Rosa,Cabrero-Antonino, Jose R.,Junge, Kathrin,Jackstell, Ralf,Beller, Matthias
-
supporting information
p. 11049 - 11053
(2016/10/13)
-
- Unsupported Nanoporous Gold Catalyst for Chemoselective Hydrogenation Reactions under Low Pressure: Effect of Residual Silver on the Reaction
-
For the first time, H-H dissociation on an unsupported nanoporous gold (AuNPore) surface is reported for chemoselective hydrogenation of C=C, C=C, C=N, and C=O bonds under mild conditions (8 atm H2 pressure, 90 °C). Silver doping in AuNPore, which was inevitable for its preparation through a process of dealloying of Au-Ag alloy, exhibited a remarkable difference in catalytic activity between two catalysts, Au>99Ag1NPore and Au90Ag10NPore.The former was more active and the latter less active in H2 hydrogenation, while the reverse tendency was observed for O2 oxidation. This marked contrast between H2 reduction and O2 oxidation is discussed. Further, Au>99Ag1NPore showed a high chemoselectivity toward reduction of terminal alkynes in the presence of internal alkynes which was not achieved using supported gold nanoparticle catalysts and other previously known methods. Reductive amination, which has great significance in synthesis of amines due to its atom-economical nature, was also realized using Au>99Ag1NPore, and the Au>99Ag1NPore/H2 system showed a preference for the reduction of aldehydes in the presence of imines. In addition to this high chemoselectivity, easy recovery and high reusability of AuNPore make it a promising heterogeneous catalyst for hydrogenation reactions.
- Takale, Balaram S.,Feng, Xiujuan,Lu, Ye,Bao, Ming,Jin, Tienan,Minato, Taketoshi,Yamamoto, Yoshinori
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p. 10356 - 10364
(2016/08/31)
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- Heterogeneous Catalytic Reductive Amination of Carbonyl Compounds with Ni-Al Alloy in Water as Solvent and Hydrogen Source
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The heterogeneous catalytic reductive amination of carbonyl compounds has been achieved by reactions of ammonium hydroxide and various amines with ketones and aldehydes. The process is based on the application of Raney type Ni-Al alloy in an aqueous medium. The reaction of the carbonyl compounds with the amine provided the corresponding Schiff bases that immediately underwent a reduction to provide primary and secondary amines as products. The controlled reaction of the Al content of the alloy with the solvent water generates hydrogen, and the in situ formed Raney Ni serves as a hydrogenation catalyst. The method is a simple and efficient way of preparing a broad variety of primary and secondary amines.
- Sch?fer, Christian,Ni?anci, Bilal,Bere, Matthew P.,Da?tan, Arif,T?r?k, Béla
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p. 3127 - 3133
(2016/09/09)
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- Alkylation of Amines with Alcohols and Amines by a Single Catalyst under Mild Conditions
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An efficient catalytic system for the alkylation of amines with either alcohols or amines under mild conditions has been developed, using cyclometallated iridium complexes as catalysts. The method has broad substrate scope, allowing for the synthesis of a diverse range of secondary and tertiary amines with good to excellent yields. By controlling the ratio of substrates, both mono- and bis-alkylated amines can be obtained with high selectivity. In particular, methanol can be used as the alkylating reagent, affording N-methylated products selectively. A strong solvent effect is observed for the reaction.
- Zou, Qingzhu,Wang, Chao,Smith, Jen,Xue, Dong,Xiao, Jianliang
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supporting information
p. 9656 - 9661
(2015/06/30)
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- Phosphino-amine (PN) Ligands for Rapid Catalyst Discovery in Ruthenium-Catalyzed Hydrogen-Borrowing Alkylation of Anilines: A Proof of Principle
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A general synthetic protocol for the synthesis of simple phosphino-amine (PN) ligands is described with 19 ligands being isolated in good yields. High-throughput ligand screening uncovered the success of two of these ligands for aromatic amine alkylations via ruthenium-catalyzed hydrogen borrowing reactions. The combination of N,N'-bis(diphenylphosphino)-N,N′-dimethylpropylenediamine with a ruthenium(II) source and potassium hydroxide (15 mol%) is the optimal system for selective monobenzylations of aromatic amines (method A). Over 70% isolated yields have been achieved for the formation of 14 secondary aromatic amines under mild reaction conditions (120 C and 1.05 equivalents of benzyl alcohol). On the other hand, N,N-bis(diphenylphosphino)-isopropylamine was the ligand utilized for both selective monomethylation and monoethylation reactions of aromatic amines (method B). Here the alcohol is charged as both the reaction medium and substrate and 9 examples are disclosed with all isolated yields exceeding 70%. These methods have been applied to the synthesis of important synthetic building blocks based on aminoferrocene.
- Broomfield, Lewis Marc,Wu, Yichen,Martin, Eddy,Shafir, Alexandr
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p. 3538 - 3548
(2016/01/25)
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- Synthesis, structures, and reactivity of ruthenium complexes with PNP-pincer type phosphaalkene ligands
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2,6-Bis[1-phenyl-2-(2,4,6-tri-tert-butylphenyl)-2-phosphaethenyl]pyridine (BPEP-Ph) reacts with [Ru3(CO)12] or [RuCl(η 3-allyl)(CO)3] in toluene at elevated temperatures to afford the three types of PNP-pincer complexes 1-3. The reaction of BPEP-Ph with [Ru3(CO)12] under vacuum forms a mixture of [Ru(CO) 2(BPEP-Ph)] (1) and a dicarbonylruthenium(0) complex (2); the latter complex has an unsymmetrical PNP-pincer ligand with 1-phenyl-2-phosphaethenyl and phenyl(benzo[b]phospholan-1-yl)methyl groups at the 2,6-positions of the pyridine core, which is formed by intramolecular C-H addition of a t-Bu group to the P=C bond. On the other hand, the reaction of BPEP-Ph with [RuCl(η3-allyl)(CO)3] affords a dicarbonylruthenium(II) chloride (3) with an unsymmetrical PNP-pincer ligand bearing a dearomatized pyridyl group with 1-phenyl-2-phosphaethenyl and α-(benzo[b]phospholan-1-yl)benzylidene substituents at the 2,6-positions. Treatment of 3 with i-PrOK in THF results in selective formation of 2. Complexes 1-3 have been isolated as crystalline compounds and examined in detail by IR and NMR spectroscopy, X-ray diffraction studies, and DFT calculations. Complex 1 exhibits catalytic activity toward N-alkylation of amines (RNH2) with alcohols (R′CH2OH) to give imines (RN=CHR′) as major products.
- Nakajima, Yumiko,Okamoto, Yuki,Chang, Yung-Hung,Ozawa, Fumiyuki
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p. 2918 - 2925
(2013/06/27)
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- Room temperature and solvent-free iridium-catalyzed selective alkylation of anilines with alcohols
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A bidentate iridium NHC-phosphine complex has been developed and applied to the N-monoalkylation of aromatic amines with a wide range of primary alcohols and to the N-heterocyclization of amino alcohols. This reaction resulted in high isolated product yields, even at room temperature and under solvent-free conditions. The Royal Society of Chemistry 2013.
- Li, Jia-Qi,Andersson, Pher G.
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supporting information
p. 6131 - 6133
(2013/07/26)
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- A bis(phosphaethenyl)pyridine complex of iridium(I): Synthesis and catalytic application to N-alkylation of amines with alcohols
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The iridium(I) complex [IrCl(BPEP-H)] (1), coordinated with 2,6-bis[2-(2,4,6-tri-tert-butylphenyl)-2-phosphaethenyl]pyridine (BPEP-H) as a PNP-pincer-type phosphaalkene ligand, has been synthesized and fully characterized by elemental analysis, NMR spectroscopy, and X-ray diffraction analysis. Complex 1 (1 mol %) catalyzes N-alkylation of primary and secondary amines with alcohols, leading to the selective formation of secondary and tertiary amines, respectively. Primary amines are smoothly alkylated with a variety of benzylic and aliphatic alcohols (1 or 3 equiv) at 100 C under basic conditions (CsOH, 10 mol %) to give the corresponding secondary amines in good to high yields. On the other hand, N-alkylation of secondary amines with benzyl alcohol (3 equiv) proceeds in the presence of KH2PO4 (5 mol %) at 140 C to afford tertiary amines in high yields.
- Chang, Yung-Hung,Nakajima, Yumiko,Ozawa, Fumiyuki
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p. 2210 - 2215
(2013/05/21)
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- Efficient and chemoselective direct reductive amination of aromatic aldehydes catalyzed by oxo-rhenium complexes containing heterocyclic ligands
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This work describes the catalytic activity of 17 oxo-rhenium complexes containing heterocyclic ligands in the direct reductive amination of 4-nitrobenzaldehyde with 4-chloroaniline, using phenylsilane as reducing agent. In general, all of the catalysts tested gave excellent yields of the secondary amine, although, the best result was obtained with the catalytic system PhSiH3/ReOBr2(Hhmpbta)(PPh3) (2.5 mol %). This system was also applied to the synthesis of a large variety of secondary amines in good to excellent yields and tertiary amines in moderate yields, with tolerance of different functional groups.
- Bernardo, Joana R.,Sousa, Sara C.A.,Florindo, Pedro R.,Wolff, Mariusz,Machura, Barbara,Fernandes, Ana C.
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p. 9145 - 9154
(2013/09/24)
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- Construction of Dibenzazocine Skeleton by Regiocontrolled Ring-Expansion Reaction of Cyclic Oxime with DIBAL-H: Facile Synthesis of 17β-Hydroxy- steroid Dehydrogenase Type 3 Inhibitor
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Synthetic studies on a 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) inhibitor are described. The unsymmetrical dibenzazocine skeleton was constructed by a regiocontrolled ring-expansion reaction of a cyclic oxime with DIBAL-H. Georg Thieme Verlag Stuttgart · New York.
- Cho, Hidetsura,Iwama, Yusuke,Okano, Kentaro,Tokuyama, Hidetoshi
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p. 813 - 816
(2013/05/22)
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- Mechanistic investigation of the iridium-catalysed alkylation of amines with alcohols
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The [Cp*IrCl2]2-catalysed alkylation of amines with alcohols was investigated using a combination of experimental and theoretical methods. A Hammett study involving a series of para-substituted benzyl alcohols resulted in a line with a negative slope. This clearly documents that a positive charge is built up in the transition state, which in combination with the measurement of a significant kinetic isotope effect determines hydride abstraction as being the selectivity-determining step under these conditions. A complementary Hammett study using para-substituted anilines was also carried out. Again, a line with a negative slope was obtained suggesting that nucleophilic attack on the aldehyde is selectivity-determining. A computational investigation of the entire catalytic cycle with full-sized ligands and substrates was performed using density functional theory. The results suggest a catalytic cycle where the intermediate aldehyde stays coordinated to the iridium catalyst and reacts with the amine to give a hemiaminal which is also bound to the catalyst. Dehydration to the imine and reduction to the product amine also takes place without breaking the coordination to the catalyst. The fact that the entire catalytic cycle takes place with all the intermediates bound to the catalyst is important for the further development of this synthetic transformation. The Royal Society of Chemistry 2012.
- Fristrup, Peter,Tursky, Matyas,Madsen, Robert
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supporting information; experimental part
p. 2569 - 2577
(2012/04/23)
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- Iron/amino acid catalyzed direct N-alkylation of amines with alcohols
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(Chemical Equation Presented) Ironing it out: The straightforward N-alkylation using alcohols and iron/amino acid catalysis is described (see scheme). The reaction does not proceed by the conventional "borrowing hydrogen" mechanism, but appears to involve a substitution pathway (S N) at the sp3 carbon atom bearing the hydroxy group of the alcohol. Developing a catalyst that is effective at a near neutral pH was key to the successful N-alkylation.
- Zhao, Yingsheng,Foo, Siong Wan,Saito, Susumu
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supporting information; experimental part
p. 3006 - 3009
(2011/05/04)
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- N-alkylation of amines with alcohols catalyzed by a water-soluble cp*iridium complex: An efficient method for the synthesis of amines in aqueous media
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An efficient and environmentally benign catalytic system for the synthesis of various organic amines catalyzed by the water-soluble and air-stable (pentamethylcyclopentadienyl)-iridium-ammine iod- ide complex, [Cp*Ir(NH3)3][I]2 (Cp= pentamethylcyclopentadienyl), has been developed. A wide variety of secondary and tertiary amines were synthesized by the N-alkylation reactions of theoretical equivalents of amines with alcohols in water under air without a base. The synthesis of cyclic amines was also achieved by the N-alkylation of benzylamine with diols. Furthermore, the recycle use of the present water-soluble Cp*Ir catalyst was accomplished. Copyright
- Kawahara, Ryoko,Fujita, Ken-Ichi,Yamaguchi, Ryohei
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supporting information; experimental part
p. 1161 - 1168
(2011/06/24)
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- Efficient and highly chemoselective direct reductive animation of aldehydes using the system silane/oxorhenium complexes
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This work reports a novel method for direct reductive amination of aldehydes with silanes catalyzed by several high-valent oxorhenium(V) and oxorhenium (VII) complexes. The catalytic system PhSiH3/ReIO 2(PPh3)2 (2.5mol%) was very efficient for the synthesis of secondary amines and highly chemoselective, tolerating a wide range of functional groups such as -NO2, -CF3, -SO 2R, -CO2R, -F, -Cl, -Br, -I, -CN, -OH, -OCH3, -SCH3, NCOR, and double bonds. This novel method was also employed in the synthesis of tertiary amines with moderate yields.
- Sousa, Sara C. A.,Fernandes, Ana C.
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experimental part
p. 2218 - 2226
(2010/11/05)
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- Regioselective synthesis of heterocycles containing nitrogen neighboring an aromatic ring by reductive ring expansion using diisobutylaluminum hydride and studies on the reaction mechanism
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(Chemical Equation Presented) A systematic investigation of the reductive ring-expansion reaction of cyclic ketoximes fused to aromatic ringswith diisobutylaluminum hydride (DIBALH) is described. This reaction regioselectively afforded a variety of five- to eight-membered bicyclic heterocycles or tricyclic heterocycles containing nitrogen neighboring an aromatic ring, including indoline, 1,2,3,4,5,6-hexahydrobenz[b]azocine, 3,4-dihydro-2H-benzo[b] [1,4]oxazine, 2,3,4,5-tetrahydrobenzo[b][1,4]thiazepine, 1,2,3,4,5,6- hexahydroazepino[3,2-b]-indole, 2,3,4,5-tetrahydro-1H-benzothieno[2,3-b]azepine, 2,3,4,5-tetrahydro-1H-benzothieno[3,2-b]-azepine, 5,6-dihydrophenanthridine, and 5,6,11,12-tetrahydrodibenz[b, f]azocine. The reaction mechanism leading to the rearrangement was investigated on the basis of the restricted Becke three-parameter plus Lee-Yang-Parr (B3LYP) density functional theory (DFT) with the 6-31G (d) basis set. It was found that the reaction proceeds through a three-centered transition state via a stepwise mechanism because the potential energy curve along the intrinsic reaction coordinate (IRC) had twomaxima (saddle points; TS1 and TS2) and the partial phenonium cation intermediate C. In addition to cyclic ketoximes fused to aromatic rings, the reactions of various cyclic and acyclic ketoximeswere examined to investigate preference of migrating group. It was found that themore electron-rich group migrated preferentially to give the corresponding secondary amines.
- Cho, Hidetsura,Iwama, Yusuke,Sugimoto, Kenji,Mori, Seiji,Tokuyama, Hidetoshi
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experimental part
p. 627 - 636
(2010/04/29)
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- MUSCARINIC ACETYLCHOLINE RECEPTOR ANTAGONISTS
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Muscarinic Acetylcholine receptor antagonists and methods of using them are provided.
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Page/Page column 28
(2010/02/14)
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- A novel method for the reduction of imines using the system silane/MoO 2Cl2
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A novel catalytic system, silane/MoO2Cl2 (10 mol %), for the reduction of imines in excellent to moderate yields and chemoselectivity was designed. These results extend the scope of the use of MoO 2Cl2 as an eff
- Fernandes, Ana C.,Rom?o, Carlos C.
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p. 8881 - 8883
(2007/10/03)
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