- Intramolecular cyclization of aminoalkynes catalyzed by PdMo 3S4 cubane clusters
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PdMo3S4 cubane clusters [(Cp*Mo) 3(μ3-S)4Pd(L)][PF6] (Cp* = η5-C5Me5; L = dba (2), ma (3); dba = dibenzylideneacetone, ma = maleic anhydride) showed high catalytic activity for the intramolecular hydroamination of aminoalkynes to afford the corresponding cyclic imines in good yields under mild conditions. A molecular structure of 3 has been determined by X-ray diffraction study. Copyright
- Takei, Izuru,Enta, Yutaka,Wakebe, Youhei,Suzuki, Toshiaki,Hidai, Masanobu
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- Gold(I) complexes with "normal" 1,2,3-triazolylidene ligands: Synthesis and catalytic properties
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1,2,3-Triazolylidenes as versatile, strong donor ligands have currently experienced a boost in complex synthesis as well as catalytic applications. Although many examples of "abnormal" 1,2,3-triazolylidenes have been described, their "normal" congeners have been barely examined to date (for abnormal carbenes the resonance structures of the carbenes cannot be drawn without adding additional charges, but this is possible for normal carbenes). Furthermore, no instance of utilization of this new ligand class in homogeneous catalysis can be found. Therefore, this work presents a variety of potential precatalysts descending from "normal" 1,2,3-triazolylidene Au chloride complexes. Synthesis and thorough characterization of the new compounds are presented, together with special ligand features such as buried volume and suspected anagostic interactions. The activity of the isolated precatalysts is examined in the intramolecular hydroamination of alkynes and compared with that of a popular imidazolylidene system. It is found that the activity of the best-performing "normal" 1,2,3-triazolylidene systems is quite similar to that of the imidazolylidene systems. However, mercury drop poisoning experiments suggest that improvements in ligand design are required to enhance catalyst stability.
- Schaper, Lars-Arne,Wei, Xuhui,Hock, Sebastian J.,Poethig, Alexander,Oefele, Karl,Cokoja, Mirza,Herrmann, Wolfgang A.,Kuehn, Fritz E.
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- Inhibitors of polyamine biosynthesis. 3. (±) 5 amino 2 hydrazino 2 methylpentanoic acid, an inhibitor of ornithine decarboxylase
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(±) 5 Amino 2 hydrazino 2 methylpentanoic acid [α hydrazino α methyl (±) ornithine] was obtained from 1 phthalimidopentan 4 one by treatment with hydrazine and KCN followed by acid hydrolysis. The title compound was found in vitro to be a potent competitive inhibitor of ornithine decarboxylase obtained from the prostate glands of rats. This inhibition was abolished at high concentrations of pyridoxal phosphate. The title compound also blocked the increase in putrescine levels normally observed in bovine lymphocytes transformed by conconavalin A.
- Abdel Monem,Newton,Weeks
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- Mononuclear rhodium(I) complexes with chelating N-heterocyclic carbene ligands - Catalytic activity for intramolecular hydroamination
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The mononuclear cationic RhI complexes [Rh(cod)(mdd)] +X- and [Rh(CO)2(mdd)]+X - (X = BPh4, PF6) containing the chelating bidentate N-heterocyclic carbene ligand 1,1′-methylene - 3,3′-dimethyldiimidazoline-2,2′-diylidene (mdd) have been synthesised and spectroscopically characterised. The complexes [Rh(cod)(mdd)]+BPh4- and [Rh(CO) 2(mdd)]+PF6- have also been characterised by X-ray crystallography. The dicarbonyl complexes catalyse the intramolecular hydroamination of 4-pentyn-1-amine to 2-methyl-1-pyrroline. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Burling, Suzanne,Field, Leslie D.,Li, Hsiu L.,Messerle, Barbara A.,Turner, Peter
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- 3-AZABICYCLO(3.1.0)HEXANE DERIVATIVES HAVING KDM5 INHIBITORY ACTIVITY AND USE THEREOF
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The present invention provides KDM5 inhibitor. The compound disclosed herein represented by the general formula (I) : wherein all symbols have the same meanings as the definitions described in the specification; or a salt thereof is useful as a prophylact
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Paragraph 0632
(2021/11/13)
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- Dendrimeric and Corresponding Monometallic Iridium(III) Catalysts Bound to Carbon Nanotubes Used in Hydroamination Transformations
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This report describes the synthesis of a carbon nanotube-bound dendrimer and three carbon nanotube-bound monometallic complexes and their use as catalysts. The polyamidoamine third generation dendrimer used here incorporates pyrazole-triazole moieties suitable for ligating iridium(III) centres. The monometallic complexes use the same pyrazole-triazole ligands coordinated to an iridium(III) centre. All catalysts were characterized using ICP-AES and XPS to evaluate their metal loadings on the carbon surface with significantly higher relative weight percentage of iridium determined for the denrimeric species. The catalytic activity and practicality of the formed catalysts were tested using two different intramolecular hydroamination reactions.
- Pernik, Indrek,Desmecht, Antonin,Messerle, Barbara A.,Hermans, Sophie,Riant, Olivier
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supporting information
p. 3448 - 3457
(2021/08/30)
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- Synthesis method of 2-methyl pyrroline
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The invention discloses a synthesis method of 2-methyl pyrroline. The preparation method comprises the following steps: adding valeryl chloride and phthaloyl potassium salt into a high-boiling-point solvent and carrying out heating reflux for 5 to 15 hours; and S2, after the reaction liquid is cooled, filtering the reaction liquid, concentrating the reaction liquid, adding methanol for pulping toobtain a crude product, adding the crude product obtained in S1 into hydrochloric acid for heating reflux, after the reaction is completed, performing concentrating to dryness, adding water into residual liquid for dissolving, adjusting the pH value to be about 11 by using sodium carbonate, performing extracting for 3-5 times by using dichloromethane, and performing concentrating and drying, and distilling to obtain a product. According to the synthetic method of the 2-methyl pyrroline, disclosed by the invention, the used initial raw materials are easy to obtain, the preparation is convenient, the enlarged production is easy, the intermediate product is stable, and the collection efficiency is high.
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Paragraph 0014; 0016; 0018
(2020/06/16)
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- A Commercially Available and User-Friendly Catalyst for Hydroamination Reactions under Technical Conditions
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The activity of a simple, commercially available copper salt, [Cu(NCMe)4](BF4) in intramolecular hydroamination reactions of alkynes and allenes is presented. Reactions were successfully carried out in technical acetonitrile in the presence of air. While attempts of alkene hydroamination failed, this catalyst was also found active in intermolecular aza-Michael reactions.
- Zelenay, Benjamin,Munton, Peter,Tian, Xiaojie,Díez-González, Silvia
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p. 4725 - 4730
(2019/08/01)
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- Simple and reactive Ir(i) N-heterocyclic carbene complexes for alkyne activation
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Two simple unsymmetrical monometallic Ir(i) complexes with an N-heterocyclic carbene ligand and an analogous bimetallic Ir(i) complex were synthesised. These complexes were found to be extremely active catalysts for a range of C-X (X = N or O) and Si-N bond forming reactions involving alkyne and imine activation for dihydroalkoxylation, hydroamination and hydrosilylation reactions. These catalysts exhibited reaction rates far exceeding those of other Rh(i) and Ir(i) complexes previously reported. In addition, a small change to the ligand design (phenyl vs. mesityl) substantially affected both the reactivity and product selectivity of the catalyst. The Ir(i) complex bearing a mesitylene wingtip provided unprecedented regioselectivity in the dihydroalkoxylation reaction and a new kinetic product from the typical hydrosilylation protocol of 2-benyzlpyrroline to produce an N-silylaminoalkene. Our mechanistic studies indicated that this transformation proceeded via a dehydrogenative coupling mechanism.
- Gatus, Mark R. D.,Pernik, Indrek,Tompsett, Joshua A.,Binding, Samantha C.,Peterson, Matthew B.,Messerle, Barbara A.
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supporting information
p. 4333 - 4340
(2019/04/01)
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- Enhancements in catalytic reactivity and selectivity of homobimetallic complexes containing heteroditopic ligands
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Rh(i) and Ir(i) homobimetallic complexes were synthesised using a heteroditopic ligand system on a xanthene scaffold containing a monodentate N-heterocyclic carbene ligand and a bidentate bis(pyrazol-1-yl)methane ligand. The complexes were tested as catalysts for the two-step dihydroalkoxylation and two-step hydroamination/hydrosilylation reactions. This is the first known report of an organometallic group 9 complex, Ir(i) bimetallic complex, 13, to selectively favour the opposite spirocyclisation product from that reported in the literature, 14cvs.14b. The Ir(i) homobimetallic complex catalyses the intramolecular hydroamination reaction of alkynamines efficiently and proved to be a highly active catalyst for promoting the subsequent hydrosilylation of the pyrrolines; completing the hydrosilylation reactions in less than 40 seconds. A chloro-bridged bimetallic species was observed in the solid state, revealing that the COD co-ligands present underwent an oxidation.
- Gatus, Mark R. D.,McBurney, Roy T.,Bhadbhade, Mohan,Messerle, Barbara A.
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p. 7457 - 7466
(2017/07/10)
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- MAu2GeS4-Chalcogel (M = Co, Ni): Heterogeneous Intra- and Intermolecular Hydroamination Catalysts
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High surface area macroporous chalcogenide aerogels (chalcogels) MAu2GeS4 (M = Co, Ni) were prepared from K2Au2GeS4 precursor and Co(OAc)2 or NiCl2 by one-pot sol-gel metathesis reactions in aqueous media. The MAu2GeS4-chalcogels were screened for catalytic intramolecular hydroamination of 4-pentyn-1-amine substrate at different temperatures. 87% and 58% conversion was achieved at 100 °C, using CoAu2GeS4- and NiAu2GeS4-chalcogels respectively, and the reaction kinetics follows the first order. It was established that the catalytic performance of the aerogels is associated with the M2+ centers present in the structure. Intermolecular hydroamination of aniline with 1-R-4-ethynylbenzene (R = -H, -OCH3, -Br, -F) was carried out at 100 °C using CoAu2GeS4-chalcogel catalyst, due to its promising catalytic performance. The CoAu2GeS4-chalcogel regioselectively converted the pair of substrates to respective Markovnikov products, (E)-1-(4-R-phenyl)-N-phenylethan-1-imine, with 38% to 60% conversion.
- Davaasuren, Bambar,Emwas, Abdul-Hamid,Rothenberger, Alexander
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p. 9609 - 9616
(2017/08/26)
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- Gold(III) NHC Complexes for Catalyzing Dihydroalkoxylation and Hydroamination Reactions
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A gold(III) complex of an N-heterocyclic carbene based hemilabile ligand with two pendant pyrazole arms (1,3-bis((1H-pyrazol-3-yl)methyl)-2,3-dihydro-1H-imidazole, LH) was synthesized. Complex [LAu(III)Cl3] is an excellent catalyst for promoting dihydroalkoxylation at room temperature, even catalyzing this reaction at 0 °C. [LAu(III)Cl3] is one of the most efficient catalysts reported to date for the spirocyclization of alkynyl diols. Furthermore, [LAu(III)Cl3] catalyzed intra- and intermolecular hydroamination reactions, achieving good to excellent conversions. [LAu(III)Cl3] is a more efficient catalyst than a gold(I) analogue, [LAu(I)Cl]. The dependence of the quantity of weakly coordinating anion [BArF4]- ((3,5-trifluoromethyl)phenyl borate) present on catalysis efficiency was probed for the dihydroalkoxylation reaction. X-ray diffraction analysis of single crystals demonstrated the solid-state structure of gold complexes [LAu(III)Cl3] and [LAu(I)Cl], which displayed the expected square-planar and linear coordination geometries, respectively.
- Nair, Ashwin G.,McBurney, Roy T.,Gatus, Mark R. D.,Binding, Samantha C.,Messerle, Barbara A.
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supporting information
p. 12067 - 12075
(2017/10/10)
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- Highly versatile heteroditopic ligand scaffolds for accommodating group 8, 9 & 11 heterobimetallic complexes
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Two highly versatile xanthene scaffolds containing pairs of heteroditopic ligands were found to be capable of accommodating a range of transition metal ions, including Au(i), Ir(i), Ir(iii), Rh(i), and Ru(ii) to generate an array of heterobimetallic complexes. The metal complexes were fully characterised and proved to be stable in the solid and solution state, with no observed metal-metal scrambling. Heterobimetallic complexes containing the Rh(i)/Ir(i) combinations were tested as catalysts for the two-step dihydroalkoxylation reaction of alkynediols and sequential hydroamination/hydrosilylation reaction of alkynamines.
- Gatus, Mark R. D.,Bhadbhade, Mohan,Messerle, Barbara A.
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p. 14406 - 14419
(2017/11/06)
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- Diverse reactivity of a tricoordinate organoboron L2PhB: (L = oxazol-2-ylidene) towards alkali metal, group 9 metal, and coinage metal precursors
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The reactivity of a tricoordinate organoboron L2PhB: (L = oxazol-2-ylidene) 1 towards metal precursors and its coordination chemistry were comprehensively studied. While the boron center in 1 is reluctant to coordinate to the alkali metals in their trifluoromethanesulfonate salts (MOTf) (M = Li, Na, K), the unprecedented compound 2 containing two L2PhB: units linked by a cyclic Li(OTf)2Li spacer was obtained from the reaction of 1 with LiOTf. Treatment of 1 with group 9 metal complexes [MCl(COD)]2 (M = Rh, Ir) afforded the first zwitterionic rhodium(i)-boronium complex 3 and the iridium(iii)-borane complex 4, respectively. The reaction pathway may involve C-H activation followed by proton migration from the metals to the boron center, demonstrating the first example of the deprotonation of metal hydrides by a basic boron. In the reactions with coinage metals, 1 could act as a two-electron reducing agent towards the metal chlorides MCl (M = Cu, Ag, Au). Meanwhile, the reaction of 1 with gold chloride supported by a N-heterocyclic carbene (NHC) produced a heteroleptic cationic gold complex [(L2PhB)Au(NHC)]Cl (6) featuring both carbene and L2PhB: ligands on the gold atom. In contrast, an isolable gold chloride complex (L2PhB)AuCl (8) was obtained by direct complexation between 1 and triphenylphosphine-gold chloride via ligand exchange. X-ray diffraction analysis and computational studies revealed the nature of the B:→Au bonding interaction in complexes 6 and 8. Natural Population Analysis (NPA) and Natural Bond Orbital (NBO) analysis support the strong σ-donating property of the L2PhB: ligand. Moreover, preliminary studies showed that complex 8 can serve as an efficient precatalyst for the addition of X-H (X = N, O, C) to alkynes under ambient conditions, demonstrating the first application of a metal complex featuring a neutral boron-based ligand in catalysis.
- Kong, Lingbing,Ganguly, Rakesh,Li, Yongxin,Kinjo, Rei
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p. 2893 - 2902
(2015/08/26)
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- The advantages of covalently attaching organometallic catalysts to a carbon black support: Recyclable Rh(I) complexes that deliver enhanced conversion and product selectivity
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Pure carbon black (CB) was covalently attached to a bidentate nitrogen coordination motif with a carbon-carbon bond by spontaneous reaction with an in situ generated ligand precursor. The functionalized support was treated with [Rh(CO)2(μ-Cl)]2 to form a heterogeneous carbon-based support covalently linked to a well defined Rh(i) coordination complex. The hybrid material was characterized using X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), Infrared (IR) spectroscopy and inductively coupled plasma mass spectrometry (ICP-MS). The CB-supported Rh(i) catalyst was active in both hydroamination and dihydroalkoxylation reactions achieving turnover numbers approaching 1000 and was readily recycled. The selectivity of an intramolecular dihydroalkoxylation reaction was significantly improved by covalently anchoring the catalyst to the CB surface.
- Tregubov, Andrey A.,Walker, D. Barney,Vuong, Khuong Q.,Gooding, J. Justin,Messerle, Barbara A.
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supporting information
p. 7917 - 7926
(2015/05/05)
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- Characterization of three novel enzymes with imine reductase activity
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Imine reductases (IRED) are promising catalysts for the synthesis of optically pure secondary cyclic amines. Three novel IREDs from Paenibacillus elgii B69, Streptomyces ipomoeae 91-03 and Pseudomonas putida KT2440 were identified by amino acid or structural similarity search, cloned and recombinantly expressed in E. coli and their substrate scope was investigated. Besides the acceptance of cyclic amines, also acyclic amines could be identified as substrates for all IREDs. For the IRED from P. putida, a crystal structure (PDB-code 3L6D) is available in the database, but the function of the protein was not investigated so far. This enzyme showed the highest apparent E-value of approximately Eapp = 52 for (R)-methylpyrrolidine of the IREDs investigated in this study. Thus, an excellent enantiomeric purity of >99% and 97% conversion was reached in a biocatalytic reaction using resting cells after 24 h. Interestingly, a histidine residue could be confirmed as a catalytic residue by mutagenesis, but the residue is placed one turn aside compared to the formally known position of the catalytic Asp187 of Streptomyces kanamyceticus IRED.
- Gand,Müller,Wardenga,H?hne
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p. 126 - 132
(2015/02/19)
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- METHOD FOR PRODUCING OPTICALLY ACTIVE ALPHA-SUBSTITUTED PROLINE
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The present invention aims to provide an industrial method practically suitable for producing optically active α-substituted prolines from an acyclic ketone compound by a small number of steps under mild conditions. The present invention relates to a production method of an optically active α-substituted proline (4) and/or an optically active α-substituted prolinamide (5), including (a) reacting an acyclic ketone compound (1) with at least one selected from ammonia, an ammonium salt, primary amine and a salt of primary amine, and a cyanating agent to give a cyclic nitrogen-containing compound (2), (b) hydrating the cyclic nitrogen-containing compound (2) to give an α-substituted prolinamide (3), and (c) resolving the α-substituted prolinamide (3) by one or more of (d) enzymatical hydrolysis, (e) resolution by diastereomeric salt formation, and (f) separation by column chromatography.
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Paragraph 0167
(2014/05/06)
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- Cationic Rh and Ir complexes containing bidentate imidazolylidene-1,2,3- triazole donor ligands: Synthesis and preliminary catalytic studies
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A series of new cationic Rh(i), Rh(iii) and Ir(iii) complexes containing hybrid bidentate N-heterocyclic carbene-1,2,3-triazolyl donor of general formulae [Rh(CaT)(COD)]BPh4 (2a-d), [Rh(CaT)(CO)2]BPh 4 (3a-d) and [M(CaT)(Cp*)Cl]BPh4 (M = Rh, 4a-d; M = Ir, 5a-c), where CaT = bidentate N-heterocyclic carbene-triazolyl ligands, COD = 1,5-cyclooctadiene and Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl, were synthesised. The imidazolium-1,2,3-triazolyl pre-ligands (1a-c and 1e-i) were readily prepared using the Cu(i) catalysed 'click reaction' between phenyl azide or benzyl azides with propargyl functionalised imidazolium salts. The single crystal solid state structures of complexes 2a-d; 3a-b; 4a-d and 5a-b confirm the bidentate coordination of the NHC-1,2,3-triazolyl ligand with the NHC coordinating via the 'normal' C2-carbon and the 1,2,3-triazolyl donor coordinating via the N3′ atom to form six membered metallocycles. These complexes are the first examples of Rh and Ir complexes containing the hybrid NHC-1,2,3-triazolyl ligands which exhibit a bidentate coordination mode. A number of these complexes showed limited efficiency as catalysts for the intramolecular hydroamination of 4-pentyn-1-amine to 2-methylpyrroline.
- Vuong, Khuong Q.,Timerbulatova, Marina G.,Peterson, Matthew B.,Bhadbhade, Mohan,Messerle, Barbara A.
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p. 14298 - 14308
(2013/10/01)
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- Rh(I) complexes bearing N, N and N,P ligands anchored on glassy carbon electrodes: Toward recyclable hydroamination catalysts
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A series of N,N-donor ligands (bis(pyrazol-1-yl)methane (bpm), bis(N-methylimidazol-2-yl)methane (bim), 1-(phenylmethyl)-4-(1H-pyrazol-1-yl methyl)-1H-1,2,3-triazole (PyT)), and one N,P-donor ligand precursor (1-(3,5-dimethylpyrazol-1-yl)(2-bromoethane) (dmPyBr)) were synthesized and functionalized with aniline. Diazotization of the aniline into an aryl diazonium, using nitrous acid in aqueous conditions, was performed in situ such that the ligands could be reductively adsorbed onto glassy carbon electrode surfaces. The N,N-donor ligands (bpm, bim, PyT) were immobilized in a single step, while several steps were required to immobilize the N,P-donor ligand (dmPyP) to prevent oxidation of the phosphine group. The complexation of the anchored ligands with the metal complex precursor ([Rh(CO)2(μ-Cl)] 2) led to the formation of anchored Rh(I) complexes with each of the ligands (bpm, bim, PyT, dmPyP). X-ray photoelectron spectroscopy (XPS) confirmed the formation of the anchored ligands as well as the anchored complexes. The surface coverage of functionalized electrodes was estimated by means of cyclic voltammetry, and the nature of the coverage was close to being a monolayer for each immobilized complex. The anchored Rh(I) complexes were active as catalysts for the intramolecular hydroamination of 4-pentyn-1-amine to form 2-methyl-1-pyrroline.
- Tregubov, Andrey A.,Vuong, Khuong Q.,Luais, Erwann,Gooding, J. Justin,Messerle, Barbara A.
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supporting information
p. 16429 - 16437
(2013/12/04)
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- New rhodium(I) and iridium(I) complexes containing mixed pyrazolyl-1,2,3-triazolyl ligands as catalysts for hydroamination
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Two new bidentate pyrazolyl-triazolyl donor ligands, 4-((1H-pyrazol-1-yl) methyl)-1-benzyl-1H-1,2,3-triazole, PyT (1a), and 4-((1H-pyrazol-1-yl)methyl)-1- phenyl-1H-1,2,3-triazole, PyS (1b), were synthesized using the copper(I)-catalyzed "click" reaction between 1-propargylpyrazole and benzyl azide or phenyl azide, respectively. Cationic rhodium(I) and iridium(I) complexes containing the new N-N′ ligands of the general formulas [M(N-N′)(COD)]X (M = Rh or Ir, N-N′ = PyT or PyS, and X = BPh 4- or BArF4- (tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) 2a-c for Rh and 3a-c for Ir) and [M(N-N′)(CO)2]X (M = Rh or Ir, N-N′ = PyT or PyS, and X = BPh4- or BArF4-4a-d for Rh and 5a-d for Ir) were successfully prepared and fully characterized. The solid-state structures of eight of these complexes were determined using single-crystal X-ray diffraction and show that the triazolyl moiety coordinates to the metal center via the N3′ atom, forming six-membered metallacycles. These metallacycles adopted a distorted boat conformation in all of the structures determined. The M-N(triazole) bonds were found to be slightly shorter than the M-N(pyrazole) bonds, illustrating the stronger donating capacity of the triazolyl donor in comparison to that of the pyrazolyl donor. All of the cationic rhodium and iridium complexes reported here are catalytically active for the intramolecular hydroamination of 4-pentyn-1-amine (6) to 2-methyl-1-pyrroline (7) at 60 °C, with TOFs > 400 h-1 in many cases. The dicarbonyl complexes [M(N-N′)(CO)2]BAr F4 (M = Rh or Ir) 4c,d and 5c,d were efficient as catalysts for the intramolecular cyclization of nonterminal alkynamines (8a,b) to cyclic imines (9a,b) via the hydroamination reaction and the cyclization of alkenamines (10a-c) to their corresponding cyclic amines (11a-c) also via the hydroamination reaction.
- Hua, Carol,Vuong, Khuong Q.,Bhadbhade, Mohan,Messerle, Barbara A.
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scheme or table
p. 1790 - 1800
(2012/04/23)
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- Purification and characterization of a novel (R)-imine reductase from Streptomyces sp. GF3587
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The (R)-imine reductase (RIR) of Streptomyces sp. GF3587 was purified and characterized. It was found to be a NADPH-dependent enzyme, and was found to be a homodimer consisting of 32 kDa subunits. Enzymatic reduction of 10mM 2-methyl-1-pyrroline (2-MPN) resulted in the formation of 9.8mM (R)-2-methylpyrrolidine ((R)-2-MP) with 99% e.e. The enzyme showed not only reduction activity for 2-MPN at neutral pH (6.5- 8.0), but also oxidation activity for (R)-2-MP under alkaline pH (10-11.5) conditions. It appeared to be a sulfhydryl enzyme based on the sensitivity to sulfhydryl specific inhibitors. It was very specific to 2-MPN as substrate.
- Mitsukura, Koichi,Suzuki, Mai,Shinoda, Sho,Kuramoto, Tatsuya,Yoshida, Toyokazu,Nagasawa, Toru
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experimental part
p. 1778 - 1782
(2012/02/02)
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- The reaction of cyclic imines with the Ruppert-Prakash reagent. Facile approach to α-trifluoromethylated nornicotine, anabazine, and homoanabazine
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We have demonstrated that the Ruppert-Prakash reagent is able to react with a number of cyclic imines under acidic condition to afford the corresponding α-trifluoromethyl derivatives of nitrogen heterocycles. 5-7-Membered cyclic imines bearing various alkyl, aryl or heterocyclic group were successfully involved in this transformation. Novel trifluoromethylated analogues of nicotine, anabasine, and homoanabasine alkaloids were synthesized.
- Shevchenko, Nikolay E.,Vlasov, Katja,Nenajdenko, Valentine G.,R?schenthaler, Gerd-Volker
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scheme or table
p. 69 - 74
(2011/02/27)
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- Improving intramolecular hydroamination Rh(i) and Ir(i) catalysts through targeted ligand modification
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A series of complexes containing the phosphino-pyrazolyl ligand 1-(2-(diphenylphosphino)phenyl)pyrazole (PyPhP) and 1-(2-(diphenylphosphino) ethyl)pyrazole (PyP) were synthesized: [Ir(PyPhP)(COD)]BPh4, [Ir(PyPhP)(CO)2]BPh4, Rh(PyPhP)(CO)Cl and Ir(PyPhP)(CO)Cl. The complexes Rh(PyP)(CO)OSO2CF3 and Rh(PyPhP)(CO) OSO2CF3 were also synthesized, using the parent complexes Rh(PyP)(CO)Cl and Rh(PyPhP)(CO)Cl. The solid-state structures of the new complexes were determined by X-ray diffraction analysis. The cationic Ir(i) complex [Ir(PyPhP)(COD)]BPh4 was found to be a highly efficient catalyst for the intramolecular hydroamination of 4-pentyn-1-amine, achieving a turnover rate of 1500 h-1, with >98% conversion in 6 minutes. The efficiency of the catalyzed hydroamination of 4-pentyn-1-amine using the neutral Ir(i) and Rh(i) complexes as catalysts was significantly improved by generating active catalysts in situ through abstraction of a chloride ligand by reaction with AgOSO2CF3, TMSOSO2CF3 or NaBPh4. The catalytic efficiency of the catalysts generated from Ir(PyP)(CO)Cl and a sodium salt were found to be inversely proportional to the coordinating strength of the counter-ion of the sodium salt. Rh(PyP)(CO)OSO 2CF3 is a more efficient catalyst for the cyclization of 4-pentyn-1-amine than the complex generated in situ from AgOSO 2CF3 and chloride complex Rh(PyP)(CO)Cl indicating that the higher lability of the triflate co-ligand of Rh(PyP)(CO)OSO 2CF3, compared to the chloride co-ligand of Rh(PyP)(CO)Cl, enhances the catalytic activity of the Rh(i) complexes.
- Beeren, Sophie R.,Dabb, Serin L.,Edwards, Gavin,Smith, Matthew K.,Willis, Anthony C.,Messerle, Barbara A.
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experimental part
p. 1200 - 1208
(2010/08/08)
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- Intramolecular hydroamination catalysed by Ag complexes stabilised in situ by bidentate ligands
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A series of silver complexes generated in situ from AgOSO2CF3 (AgOTf) and a range of bidentate ligands were investigated as catalysts for the intramolecular hydroamination of 4-pentyn-1-amine. A variety of P- and N-donor ligands were tested including the novel pyrazole-phosphine ligand 1-(2-(diphenylphosphino)phenyl)pyrazole. The best catalyst was formed from equimolar amounts of the P,N-donor ligand 1-(2-(diphenylphosphino)ethyl)pyrazole and AgOTf, which achieved a turnover rate of 129 h-1 for the cyclisation of 4-pentyn-1-amine.
- Beeren, Sophie R.,Dabb, Serin L.,Messerle, Barbara A.
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scheme or table
p. 309 - 312
(2009/04/12)
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- Weakly coordinating counter-ions for highly efficient catalysis of intramolecular hydroamination
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A series of cationic rhodium(i) and iridium(i) complexes of the type [M(L∩L)(C2)]BArF24 (where M = Rh or Ir, L∩L = bis(pyrazol-1-yl)methane (bpm), bis(N-methylimidazol-2-yl)methane (bim) or 1-(2-(diphenylphosphino)ethyl)-3,5- diphenylpyrazole (Ph2PyP), C2 = 1,5-cyclooctadiene (COD) or (CO)2 and BArF24 = tetrakis[3,5- bis(trifluoromethyl)phenyl]borate) were synthesised in good yields. The solid-state structure of a number of complexes, including [Ir(Ph 2PyP)(COD)]BArF24, [Ir(bpm)(COD)]BAr F24 and [Ir(bim)(COD)]BArF24 was determined using X-ray crystallography. The efficiency of the complexes as catalysts for the intramolecular hydroamination of 4-phenyl-3-butyn-1-amine, 4-pentyn-1-amine and 2-(2-phenylethynyl)aniline was established. The incorporation of the BArF24- counter-ion in the Rh(i) and Ir(i) complexes was found to significantly improve the catalytic activity of the complexes, compared to the analogous Rh(i) and Ir(i) complexes containing BPh4- as the counter-ion. Excellent conversions were achieved for the cyclisation of 2-(2-phenylethynyl)aniline to 2-phenylindole using [Rh(bpm)(CO)2]BArF24 as a catalyst. The use of a microwave reactor for enhancing the catalysed reactions was also investigated. The Royal Society of Chemistry 2009.
- Dabb, Serin L.,Ho, Joanne H. H.,Hodgson, Richard,Messerle, Barbara A.,Wagler, Joerg
-
experimental part
p. 634 - 642
(2009/05/06)
-
- Rhodium(I) and iridium(I) complexes containing bidentate phosphine-imidazolyl donor ligands as catalysts for the hydroamination and hydrothiolation of alkynes
-
A series of novel cationic and neutral rhodium and iridium complexes containing bidentate phosphine-imidazolyl donor ligands of the general formulae [M(ImP)(COD)]BPh4 (M = Rh, ImP = ImP2, 3; ImP1a, 4a; ImP1b, 4b and M = Ir, ImP = ImP2, 5; ImP1a, 6a and ImP1b, 6b), [Ir(ImP)(CO)2]BPh 4 (ImP = ImP2, 7; ImP1a, 8a and ImP1b, 8b), [Rh(ImP1b)(CO) 2]BPh4 (10b) and [M(ImP)(CO)Cl] (M = Rh, ImP = ImP2, 11; ImP1b, 12 and M = Ir, ImP = ImP2, 13; ImP1b, 14) where COD = 1,5-cyclooctadiene, ImP2 = 1-methyl-2-[(2-(diphenylphosphino)ethyl]imidazole, 1; ImP1a = 1-methyl-2-[(diphenylphosphino)methyl]imidazole, 2a and ImP1b = 2-[(diisopropylphosphino)methyl]-1-methylimidazole, 2b were successfully synthesised. The solid state structures of 3, 6a, 11 and 12 were determined by single crystal X-ray diffraction analysis. A number of these complexes are effective as catalysts for the intramolecular hydroamination of 4-pentyn-1-amine to 2-methyl-1-pyrroline. The cationic complexes are significantly more effective than analogous neutral complexes. The cationic iridium complex 8b, containing the phosphine-imidazolyl ligand with the bulky isopropyl groups on the phosphorus donor, is more efficient than analogous complexes with the phenyl substituents on the phosphorus donor atom, 7 and 8a. The complexes 7-8b are also moderately effective in catalysing the addition of thiophenol to a range of terminal alkynes. In contrast to the hydroamination reaction, placement of the isopropyl group on the phosphorus donor leads to a decrease in the reactivity of the resulting metal complexes as catalysts for the hydrothiolation reaction.
- Field, Leslie D.,Messerle, Barbara A.,Vuong, Khuong Q.,Turner, Peter
-
scheme or table
p. 3599 - 3614
(2009/09/07)
-
- Intramolecular hydroamination of aminoalkynes with silver-phenanthroline catalysts
-
(Chemical Equation Presented) Intramolecular hydroamination of several aminoalkynes catalyzed by silver-phenanthroline complexes is reported. This catalyst system complements previous protocols by employing air- and moisture-stable complexes without compromising activity or reaction control. Some of the hydroamination products are subject to a useful aerobic oxidation. Silver-phenanthroline complexes have successfully demonstrated efficacy in the desymmetrization of a prochiral diyne.
- Carney, Jeffrey M.,Donoghue, Patrick J.,Wuest, William M.,Wiest, Olaf,Helquist, Paul
-
supporting information; experimental part
p. 3903 - 3906
(2009/07/09)
-
- Constrained geometry organoactinides as versatile catalysts for the intramolecular hydroamination/cyclization of primary and secondary amines having diverse tethered C-C unsaturation
-
A series of "constrained geometry" organoactinide complexes, (CGC)An(NMe)2 (CGC = Me2-Si(η5-Me 4C5)(tBuN); An = Th, 1; U, 2), has been prepared via efficient in situ, two-step protodeamination routes in good yields and high purity. Both 1 and 2 are quantitatively converted to the neutrally charged, solvent-free dichlorides (1-Cl2, 2-Cl2) and slightly more soluble diiodides (1-I2, 2-I2) with excess Me3Si-X (X = Cl, I) in non-coordinating solvents. The new complexes were characterized by NMR spectroscopy, elemental analysis, and (for 1 and 2) single-crystal X-ray diffraction, revealing substantially increased metal coordinative unsaturation vs the corresponding Me2SiCp″ 2AnR2 (Cp″ = η5-Me4C 5; An = Th, R = CH2-(SiMe3), 3; An = U, R = CH2Ph, 4) and Cp′2AnR2 (Cp′ = η5-Me5C5 ; An = Th, R = CH 2(SiMe3), 5; An = U, R = CH2(SiMe3), 6) complexes. Complexes 1-6 exhibit broad applicability for the intramolecular hydroamination of diverse C-C unsaturations, including terminal and internal aminoalkenes (primary and secondary amines), aminoalkynes (primary and secondary amines), aminoallenes, and aminodienes. Large turnover frequencies (N t up to 3000 h-1) and high regioselectivities (≥95%) are observed throughout, along with moderate to high diastereoselectivities (up to 90% trans ring closures). With several noteworthy exceptions, reactivity trends track relative 5f ionic radii and ancillary ligand coordinative unsaturation. Reactivity patterns and activation parameters are consistent with a reaction pathway proceeding via turnover-limiting C=C/C=C insertion into the An-N σ-bond.
- Stubbert, Bryan D.,Marks, Tobin J.
-
p. 4253 - 4271
(2008/02/01)
-
- Scandium(III) catalysis of transimination reactions. Independent and constitutionally coupled reversible processes
-
Sc(OTf)3 efficiently catalyzes the self-sufficient transimination reaction between various types of C=N bonds in organic solvents, with turnover frequencies up to 3600 h-1 and rate accelerations up to 6 × 105. The mechanism of the crossover reaction in mixtures of amines and imines is studied, comparing parallel individual reactions with coupled equilibria. The intrinsic kinetic parameters for isolated reactions cannot simply be added up when several components are mixed, and the behavior of the system agrees with the presence of a unique mediator that constitutes the core of a network of competing reactions. In mixed systems, every single amine or imine competes for the same central hub, in accordance with their binding affinity for the catalyst metal ion center. More generally, the study extends the basic principles of constitutional dynamic chemistry to interconnected chemical transformations and provides a step toward dynamic systems of increasing complexity.
- Giuseppone, Nicolas,Schmitt, Jean-Louis,Schwartz, Evan,Lehn, Jean-Marie
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p. 5528 - 5539
(2007/10/03)
-
- Bis(phosphinimino)methanides as ligands in divalent lanthanide and alkaline earth chemistry - Synthesis, structure, and catalysis
-
Divalent bis(phosphinimino)methanide lanthanide complexes of composition [{(Me3SiNPPh2)2CH}EuI(THF)]2 and [{(Me3SiNPPh2)2CH}YbI(THF)2] have been prepared by a salt metathesis reactions of K{CH(PPh2NSiMe 3)2} and LnI2. Further reactions of these complexes with [K(THF)nN(PPh2)2] led selectively to the heteroleptic amido complexes [{(Me3SiNPPh 2)2CH}Ln{(Ph2P)2N}(THF)] (Ln = Eu, Yb). The ytterbium complex can also be obtained by reduction of [{CH(PPh 2NSiMe3)2}Yb{(Ph2P)2N}Cl] with elemental potassium. The single crystals of [{(Me3SiNPPh 2)2CH}Ln{(Ph2P)2N}(THF)] contain enantiomerically pure complexes. As a result of the similar ionic radii of the divalent lanthanides and the heavier alkaline earth metals some similarities in coordination chemistry of the bis(phosphinimino)methanide ligand were anticipated. Therefore, MI2 (M = Ca, Sr, Ba) was reacted with K{CH(PPh2NSiMe3)2} to give [{(Me 3SiNPPh2)2CH}CaI(THF)2], [{(Me 3SiNPPh2)2CH}SrI(THF)]2, and [{(Me3SiNPPh2)2CH}BaI(THF)2] 2, respectively. As expected the Sr and Eu complexes and the Ca and Yb complexes are very similar, whereas for the Ba compound, as a result of the large ion radius, a different coordination sphere is observed. For all new complexes the solid-state structures were established by single crystal X-ray diffraction. In the solid-state the {CH(PPh2NSiMe3) 2}- ligand acts as tridentate donor forming a long methanide carbon metal bond. Thus, all complexes presented can be considered as organometallic compounds. [{(Me3SiNPPh2) 2CH}YbI(THF)2] was also used as precatalyst for the intramolecular hydroamination/cyclization reaction of different aminoalkynes and aminoolefines. Good yields but moderate activities were observed.
- Panda, Tarun K.,Zulys, Agustino,Gamer, Michael T.,Roesky, Peter W.
-
p. 5078 - 5089
(2007/10/03)
-
- Convenient synthesis of melatonin analogues: 2- and 3-substituted -N-acetylindolylalkylamines
-
A new method for the synthesis of 2- and 3-substituted indolylalkylamides, derivatives of melatonin, from arylhydrazines and amidoketones by the Fischer reaction was elaborated. The amidoketones can be easily prepared from cyclic imines by reaction with acylpyridinium chloride. This method is a one-step synchronous creation of the selected alkylamide fragment and the indole core. Variation of the arylhydrazines create the desired substituents in the carbocycle of indolylalkylamides and suitable choice of amidoketone can direct the amidoalkyl chain to the 2- or 3-position of the indole. Graphical Abstract
- Nenajdenko, Valentine G.,Zakurdaev, Eugene P.,Prusov, Eugene V.,Balenkova, Elizabeth S.
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p. 11719 - 11724
(2007/10/03)
-
- Organolathanide-catalyzed regioselective intermolecular hydroamination of alkenes, alkynes, vinylarenes, di- and trivinylarenes, and methylenecyclopropanes. Scope and mechanistic comparison to intramolecular cyclohydroaminations
-
Organolanthanide complexes of the type Cp′2LnCH(SiMe 3)2 (Cp′ = η-Me5C5; Ln = La, Nd, Sm, Lu) and Me2SiCp″2LnCH(SiMe 3)2 (Cp″ = η5-Me4C 5; Ln = Nd, Sm, Lu) serve as efficient precatalysts for the regioselective intermolecular hydroamination of alkynes R′C≡CMe (R′ = SiMe3, C6H5, Me), alkenes RCH=CH2 (R = SiMe3, CH3CH2CH 2), butadiene, vinylarenes ArCH=CH2 (Ar = phenyl, 4-methylbenzene, naphthyl, 4-fluorobenzene, 4-(trifluoromethyl)benzene, 4-methoxybenzene, 4-(dimethylamino)benzene, 4-(methylthio)benzene), di- and trivinylarenes, and methylenecyclopropanes with primary amines R″NH 2 (R″ = n-propyl, n-butyl, isobutyl, phenyl, 4-methylphenyl, 4-(dimethylamino)phenyl) to yield the corresponding amines and imines. For R = SiMe3, R = CH2=CH lanthanide-mediated intermolecular hydroamination regioselectively generates the anti-Markovnikov addition products (Me3SiCH2CH2NHR″, (E)-CH 3CH=CHCH2NHR″). However, for R = CH 3CH2CH2, the Markovnikov addition product is observed (CH3CH2CH2CHNHR″CH3). For internal alkynes, it appears that these regioselective transformations occur under significant stereoelectronic control, and for R′ = SiMe 3, rearrangement of the product enamines occurs via tautomerization to imines, followed by a 1,3-trimethylsilyl group shift to stable N-SiMe 3-bonded CH2=CMeN(SiMe3)R″ structures. For vinylarenes, intermolecular hydroamination with n-propylamine affords the anti-Markovnikov addition product β-phenylethylamine. In addition, hydroamination of divinylarenes provides a concise synthesis of tetrahydroisoquinoline structures via coupled intermolecular hydroamination/subsequent intramolecular cyclohydroamination sequences. Intermolecular hydroamination of methylenecyclopropane proceeds via highly regioselective exo-methylene C=C insertion into Ln-N bonds, followed by regioselective cyclopropane ring opening to afford the corresponding imine. For the Me2SiCp″2Nd-catalyzed reaction of Me 3SiC≡CMe and H2NCH2CH2CH 2CH3, ΔH? = 17.2 (1.1) kcal mol-1 and ΔS? = -25.9 (9.7) eu, while the reaction kinetics are zero-order in [amine] and first-order in both [catalyst] and [alkyne]. For the same substrate pair, catalytic turnover frequencies under identical conditions decrease in the order Me2SiCp″2NdCH(SiMe 3)2 > Me2SiCp″ 2SmCH(SiMe3)2 > Me2SiCp″ 2LuCH(SiMe3)2 > Cp′ 2SmCH(SiMe3)2, in accord with documented steric requirements for the insertion of olefinic functionalities into lanthanide-alkyl and -heteroatom σ-bonds. Kinetic and mechanistic evidence argues that the turnover-limiting step is intermolecular C=C/C≡C bond insertion into the Ln-N bond followed by rapid protonolysis of the resulting Ln-C bond.
- Ryu, Jae-Sang,Li, George Yanwu,Marks, Tobin J.
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p. 12584 - 12605
(2007/10/03)
-
- A highly reactive titanium precatalyst for intramolecular hydroamination reactions.
-
[reaction: see text]. Tetrakisamido titanium complexes are significantly more active than Cp2TiMe2 (1) in the intramolecular hydroamination of aminoalkynes and aminoallenes. In the latter case, the regioselectivity of the transformation depends on the nature of the precatalyst, yielding the most selective and reactive catalysis with the bis(sulfonamido) complex 11.
- Ackermann, Lutz,Bergman, Robert G
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p. 1475 - 1478
(2007/10/03)
-
- The 4-oxopentyl group as a labile phosphate/thiophosphate protecting group for synthetic oligodeoxyribonucleotides
-
An efficient and economical method for the solid-phase synthesis of oligodeoxyribonucleotides and their phosphorothioate analogues is described. The method entails the use of the 4-oxopentyl group for phosphate/thiophosphate protection. Post-synthesis removal of the protecting group is easily and rapidly achieved under mild conditions at ambient temperature using either pressurized gaseous amines or concentrated ammonium hydroxide.
- Wilk, Andrzej,Chmielewski, Marcin K.,Grajkowski, Andrzej,Phillips, Lawrence R.,Beaucage, Serge L.
-
p. 5635 - 5639
(2007/10/03)
-
- Ruthenium-catalyzed intramolecular hydroamination of aminoalkynes
-
Low-valent ruthenium complexes with a π-acidic ligand, such as Ru(η6-cot)(dmfm)2 [cot=1,3,5-cyclooctatriene, dmfm=dimethyl fumarate] and Ru3(CO)12, showed high catalytic activity for the intramolecular hydroamination of aminoalkynes. The reaction is highly regioselective, in which a nitrogen atom is selectively attached to an internal carbon of alkynes to give five-, six-, and seven-membered nitrogen heterocycles as well as indoles in good to high yields.
- Kondo, Teruyuki,Okada, Takumi,Suzuki, Toshiaki,Mitsudo, Take-Aki
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p. 149 - 154
(2007/10/03)
-
- Homoleptic lanthanide amides as homogeneous catalysts for alkyne hydroamination and the Tishchenko reaction
-
The homoleptic bis(trimethylsilyl)amides of Group 3 metals and lanthanides of the general type [Ln{N(SiMe3)2}3] (1) (Ln = Y, lanthanide) represent a new class of Tishchenko precatalysts and, to a limited extent, precatalysts for the hydroamination/cyclization of aminoalkynes. It is shown that 1 is the most active catalyst for the Tishchenko reaction. This contribution presents investigations on the scope of the reaction, substrate selectivity, lanthanide-ion size-effect, and kinetic/ mechanistic aspects of the Tishchenko reaction catalyzed by 1. The turnover frequency is increased by the use of large-center metals and electron-with-drawing substrates. The reaction rate is second order with respect to the substrate. While donor atoms, such as nitrogen, oxygen, or sulfur, on the substrate decrease the turnover frequency, 1 shows a tolerance for a large number of functional groups. For the hydroamination/cyclization of aminoalkynes, 1 is less active than the well-known metallocene catalysts. On the other hand, 1 is much more readily accessible (one-step synthesis or commercially available), than the metallocenes and might therefore be an attractive alternative catalyst.
- Buergstein, Markus R.,Berberich, Helga,Roesky, Peter W.
-
p. 3078 - 3085
(2007/10/03)
-
- Reactions of N-phosphorylated aziridines with dianions derived from ethyl acetoacetate and 1,3-diketones: New route to substituted pyrrolines and pyrrolidines
-
The nucleophilic ring-opening of N-(diethoxyphosphoryl)aziridines by the dianions derived from ethyl acetoacetate and 1,3-diketones has been studied. Acid-mediated cyclisation and dephosphorylation of the resulting products to a number of substituted pyrrolines and pyrrolidines has been also investigated.
- Osowska-Pacewicka, Krystyna,Zwierzak, Andrzej
-
p. 1127 - 1137
(2007/10/03)
-
- Photoextrusion of molecular nitrogen from annulated 5-alkylidene-4,5-dihydro-1H-tetrazoles: Annulated iminoaziridines and the first triplet diazatrimethylenemethane
-
Deprotonation of the annulated tetrazolium salts 4, 6, 8, 10, and 12 with sodium or potassium hydride yields the alkyh'denedihydrotetrazoles 5, 7, 9, 11, and 13, respectively. While 5a and b are unstable, even in solution at low temperatures, 7, 9, 11, and 13 form yellow oils that are distilled under high vacuum. - Irradiation of solutions of 7, 9, and 11 in [D8]toluene at -60°C yields, besides molecular nitrogen, annulated iminoaziridines that have an exocyclic CN double bond, i.e. 14, 16, and 18, respectively. In addition, an equal amount of the isomer 19 with the endocyclic CN double bond is formed from 11. On thermolysis, 14, 16, and 18 undergo [2 + 1] cycloreversion into methyl isocyanide and the cyclic imines 15, 17, and 20, respectively. By contrast, 19 rearranges thermally to yield 18. While the doubly bridged alkylidenedihydrotetrazole 13a affords only unidentified decomposition products on photolysis, its methyl homologue 13b is converted into the hexahydronaphthyridine 22 which is also formed on thermolysis. - Irradiation of 13b in a 2-methyltetrahydrofuran or butyronitrile matrix at 77 K yields a triplet diradical showing a four-line EPR spectrum centred at 3362 G and a half-field transition (at 1669 G) with a hyperfine structure. The zero-field splitting parameters |D/hc| = 0.031 cm-1 and |E/hc| = 0.0014 cm-1 are obtained by simulation of the EPR spectrum. The signal-carrier is assigned the diazatrimethylenemethane structure 23 on the basis of the close similarity between its EPR spectrum and those of trimethylenemethane (28) and tris(N-methylimino)methane (29). - Structural features are discussed that are responsible for the observed differences between the photochemical pathways.
- Quast, Helmut,Fuss, Andreas,Nuedling, Wolfgang
-
p. 317 - 327
(2007/10/03)
-
- Synthesis and pyrolytic behaviour of thiazolidin-2-one 1,1-dioxides
-
Four examples of the chiral thiazolidin-2-one 1,1-dioxides 5 have been prepared by reaction of the appropriate amino alcohols 11 with CS2 in aqueous sodium hydroxide to give the thiazolidine-2-thiones 12, followed by oxidation with KMnO4 under phase-transfer conditions in the presence of benzoic acid, either directly or via the thiazolidin-2-ones 13. Upon flash vacuum pyrolysis (FVP) at 650°C, 5a-c decompose mainly by loss of SO2 to give an alkene and benzyl isocyanate together with other products from fragmentation of the N-benzyl group. A significant minor pathway involves net loss of CO2 and water to give the 2-phenyl-4,5-dihydrothiazoles 21 together with their aromatisation products 22 and 23. A mechanism for this new heterocyclic transformation is proposed involving initial expansion to a cyclic carbamic-sulnnic anhydride (2,1,4-oxathiazin-3-one 1-oxide). The fully assigned 13C NMR spectra are presented for 5, 12 and 13 and the 33S NMR spectrum has been obtained for 5c.
- Aitken, R. Alan,Armstrong, David P.,Galt, Ronald H. B.,Mesher, Shaun T. E.
-
p. 2139 - 2145
(2007/10/03)
-
- Organolanthanide-catalyzed intramolecular hydroamination/cyclization of aminoalkynes
-
This contribution reports the efficient and regiospecific Cp'2LnCH(SiMe3)2 (Ln = La, Nd, Sm, Lu; Cp' = η5-Me5C5)- and Me2SiCp''2LnCH(SiMe3)2 (Ln = Nd, Sm; Cp'' = η5-Me4C5)-catalyzed hydroamination/cyclization of aliphatic and aromatic aminoalkynes of the formula RC≡C(CH2)(n)NH2 to yield the corresponding cyclic imines RCH2C=N(CH2)(n-1)CH2, where R, n, N(t) h-1 (°C) = Ph, 3, 77 (21°C); Ph, 3, 2830 (60°C); Me, 3, 96 (21°C); CH2=CMeCH2, 3, 20 (21°C); H, 3, 580 (21°C); Ph, 4, 4 (21°C); Ph, 4, 328 (60°C); Ph, 5, 0.11 (60°C); and SiMe3, 3, >7600 (21°C), and of aliphatic secondary amino-alkynes of the formula RC≡C(CH2)3NHR1 to generate the corresponding cyclic enamines RCH=CNR1(CH2)2CH2 where R, R1, N(t) h-1 (°C) = SiMe3, CH2=CHCH2, 56 (21°C); H, CH2=CHCH2, 27 (21°C); SiMe3, CH2=CH(CH2)3, 129 (21°C); and H, CH2=CH(CH2)3, 47 (21°C). Kinetic and mechanistic evidence is presented arguing that the turnover-limiting step is an intramolecular alkyne insertion into the Ln-N bond followed by rapid protonolysis of the resulting Ln-C bond. The use of larger metal ionic radius Cp'2LnCH(SiMe3)2 and more open Me2SiCp''2LnCH(SiMe3)2 complexes as the precatalysts results in a decrease in the rate of hydroamination/cyclization, arguing that the steric demands in the -C≡C- insertive transition state are relaxed compared to those of the analogous aminoolefin hydroamination/cyclization.
- Li,Marks
-
p. 9295 - 9306
(2007/10/03)
-
- A Convenient Synthesis of 2-Methyl/ethyl-Δ1-pyrrolines
-
2-Methyl/ethyl-Δ1-pyrrolines have been conveniently synthesised from commercially available 2-pyrrolidone.
- Ananthapadmanabhan, S.,Raja, T. K.,Srinivasan, V.,Simon, A.
-
-
- CYCLIC β-ENAMINOESTERS DECARBOXYLATION WITH BORIC ACID : A CONVENIENT SYNTHESIS OF CYCLIC IMINES
-
Δ1-pyrrolines, Δ1-piperideines and 1-aza 1-cycloheptenes are formed in good yields from the decarboxylation of alkylated cyclic β-enaminoesters with boric acid.
- Bacos, Daniel,Celerier, Jean-Pierre,Lhommet, Gerard
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p. 2353 - 2354
(2007/10/02)
-
- La reaction d'ω-azidocetones avec la triphenylphosphine: une voie d'acces generale aux imines cycliques
-
The ω-azidoketones RC(=O)-CH(R')-(CH2)n-CH(R'')-N3 react with triphenylphosphine in anhydrous media to give 5, 6 and 7 membered cyclic imines via an intramolecular aza-Wittig reaction with good yields.A general synthesis of ω-haloketones which are the precursors of the azidoketones was also devised.
- Vaultier, M.,Lambert, P. H.,Carrie, R.
-
-
- THE USE OF ω-IODOAZIDES AS PRIMARY PROTECTED ELECTROPHILIC REAGENTS. ALKYLATION OF SOME CARBANIONS DERIVED FROM ACTIVE METHYLENE COMPOUNDS AND N,N-DIMETHYLHYDRAZONES.
-
Some carbanions derived from active methylene compounds and N,N-dimethylhydrazones were alkylated in good yields with the ω-iodoazides 3, 4 and 13 used as primary amino protected electrophilic reagents.
- Khoukhi, Mostafa,Vaultier, Michel,Carrie, Robert
-
p. 1031 - 1034
(2007/10/02)
-
- Reaction of Organolithium Reagents with Lactim Ethers: Preparation of Cyclic 2-Alkyl Imines or 2,2-Dialkyl Amines
-
The reaction of lactim ethers 1-3 with organolithium reagents has been found to be an effective method for the preparation of cyclic 2-alkyl imines 4-6.The method is most effective for the preparation of 2-aryl and sterically hindered 2-alkyl imines.In addition, treatment of 1-3 with excess organolithium provides a facile route to the rare cyclic 2,2-dialkyl amine derivatives 7-9.These reactions are characterized by mild reaction conditions and good yields and constitute a superior route to the title compounds.
- Zezza, Charles A.,Smith, Michael B.,Ross, Betsy A.,Arhin, Akwasi,Cronin, Patricia L. E.
-
p. 4397 - 4399
(2007/10/02)
-
- Synthesis and Thermolysis of O-Alkyl-N-vinylhydroxylamine Derivatives
-
Oxoiminium salts 11 a-e and 13 a-e have been prepared from the ο-chloroketones 9 a-e by oximation via the cyclic oxime ethers 10 a-e and the cyclic imine oxides 12 a-e, followed by alkylation with "Meerwein salt".The deprotonation reaction of 11 a-e and 13 a-e yields, via the regioselectively prepared intermediates 14 a-e and 17 a-e, the α, β-unsaturated imines 15 a-e and the cyclic imines 18 a-e, respectively.
- Shatzmiller, Shimon,Shalom, Eytan
-
p. 897 - 905
(2007/10/02)
-
- Palladium-Catalyzed Oxidation of Amino Alkenes to Cyclic Imines or Enamines and Amino Ketones
-
Amino alkenes of the type CH2=CH(CH2)nNH2 (n = 3,4) are cyclized to pyrrolines or piperideines under ''Wacker process''conditions.Amino alkenes with a secondary amino group yield the corresponding cyclic enamines, while tertiary amino alkenes give amino ketones.
- Pugin, B.,Venanzi, L. M.
-
p. 6877 - 6881
(2007/10/02)
-
- A New Efficient Access to Cyclic Imines
-
Cyclic imines can be conveniently prepared from ω-azidoketones by an intramolecular 'aza-Wittig' reaction.
- Lambert, Pierre H.,Vaultier, Michel,Carrie, Robert
-
p. 1224 - 1225
(2007/10/02)
-