- 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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- Catalytic Asymmetric Synthesis of Morpholines. Using Mechanistic Insights to Realize the Enantioselective Synthesis of Piperazines
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An efficient and practical catalytic approach for the enantioselective synthesis of 3-substituted morpholines through a tandem sequential one-pot reaction employing both hydroamination and asymmetric transfer hydrogenation reactions is described. Starting from ether-containing aminoalkyne substrates, a commercially available bis(amidate)bis(amido)Ti catalyst is utilized to yield a cyclic imine that is subsequently reduced using the Noyori-Ikariya catalyst, RuCl [(S,S)-Ts-DPEN] (η6-p-cymene), to afford chiral 3-substituted morpholines in good yield and enantiomeric excesses of >95%. A wide range of functional groups is tolerated. Substrate scope investigations suggest that hydrogen-bonding interactions between the oxygen in the backbone of the ether-containing substrate and the [(S,S)-Ts-DPEN] ligand of the Ru catalyst are crucial for obtaining high ee's. This insight led to a mechanistic proposal that predicts the observed absolute stereochemistry. Most importantly, this mechanistic insight allowed for the extension of this strategy to include N as an alternative hydrogen bond acceptor that could be incorporated into the substrate. Thus, the catalytic, enantioselective synthesis of 3-substituted piperazines is also demonstrated.
- Lau, Ying Yin,Zhai, Huimin,Schafer, Laurel L.
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p. 8696 - 8709
(2016/10/14)
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- Intramolecular hydroamination of aminoalkynes with silver-phenanthroline catalysts
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(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
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supporting information; experimental part
p. 3903 - 3906
(2009/07/09)
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- Constrained geometry organoactinides as versatile catalysts for the intramolecular hydroamination/cyclization of primary and secondary amines having diverse tethered C-C unsaturation
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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.
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p. 4253 - 4271
(2008/02/01)
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- Bis(phosphinimino)methanide rare earth amides: Synthesis, structure, and catalysis of hydroamination/cyclization, hydrosilylation, and sequential hydroamination/hydrosilylation
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A series of yttrium and lanthanide amido complexes [Ln{N-(SiHMe 2)2}2{CH(PPh2NSiMe3) 2}] (Ln = Y, La, Sm, Ho, Lu) were synthesized by three different pathways. The title compounds can be obtained either from [Ln{N(SiHMe 2)2}3(thf)2] and [CH 2(PPh2NSiMe3)2] or from KN-(SiHMe2)2 and [Ln(CH(PPh2NSiMe 3)2}-Cl2]2, while in a third approach the lanthanum compound was synthesized in a one-pot reaction starting from K{CH(PPh2NSiMe3)2}, LaCl3, and KN-(SiHMe2)2. All the complexes have been characterized by single-crystal X-ray diffraction. The new complexes, [Ln{N(SiHMe 2)2}2{CH(PPh2NSiMe3) 2}], were used as catalysts for hydroamination/cyclization and hydrosilylation reactions. A clear dependence of the reaction rate on the ionic radius of the center metal was observed, showing the lanthanum compound to be the most active one in both reactions. Furthermore, a combination of both reactions - a sequential hydroamination/hydrosilylation reaction - was also investigated.
- Rastaetter, Marcus,Zulys, Agustino,Roesky, Peter W.
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p. 3606 - 3616
(2008/02/10)
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- A bis(phosphinimino)methanide lanthanum amide as catalyst for the hydroamination/cyclisation, hydrosilylation and sequential hydroamination/ hydrosilylation catalysis
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[La{N(SiHMe2)2}2{CH(PPh 2NSiMe3)2}], which was obtained via an amine elimination starting from [CH2(PPh2NSiMe3) 2] and [La{N(SiHMe2)2}3(THF) 2], was used as catalyst for the hydroamination/cyclisation, the hydrosilylation and the sequential hydroamination/hydrosilylation reaction. The Royal Society of Chemistry 2006.
- Rastaetter, Marcus,Zulys, Agustino,Roesky, Peter W.
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p. 874 - 876
(2008/02/08)
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- Synthesis of bicyclic carbamates as precursors of Sedum alkaloid derivatives
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Synthesis of a N-Boc-protected piperidin-2-yl phosphine oxide starting from piperidine in three steps, followed by olefination using a variety of α,β-unsaturated aldehydes resulted in tert-butyl 2-(2′- alkenylidene)piperidine-1-carboxylates in high yields
- Szakonyi, Zsolt,D'Hooghe, Matthias,Kanizsai, Iván,Fül?p, Ferenc,De Kimpe, Norbert
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p. 1595 - 1602
(2007/10/03)
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- Amidate complexes of titanium and zirconium: A new class of tunable precatalysts for the hydroamination of alkynes
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A series of bis(amidate)group 4-bis(amido) complexes have been prepared, characterized and have been shown to be highly tunable precatalysts for both the intra- and inter-molecular hydroamination of alkynes.
- Li, Chunyu,Thomson, Robert K.,Gillon, Bronwyn,Patrick, Brian O.,Schafer, Laurel L.
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p. 2462 - 2463
(2007/10/03)
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- A one-pot procedure for the synthesis of α-amino phosphonates from alkynes
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A new and highly flexible procedure for the synthesis of α,α-disubstituted α-amino phosphonates is described with disubstituted alkynes, primary amines and diethyl or dimethyl phosphite as starting materials. The reaction sequence, which is performed as a
- Haak, Edgar,Bytschkov, Igor,Doye, Sven
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p. 457 - 463
(2007/10/03)
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- The Cp2TiMe2-catalyzed intramolecular hydroamination/cyclization of aminoalkynes
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Cp2TiMe2 has been found to be a competent catalyst for the intramolecular hydroamination/cyclization of aminoalkynes. In the presence of 5.0 mol% Cp2TiMe2, the hydroamination reactions proceed smoothly at 100-110°C to give five- and six-membered cyclic imines within 4-6 h. After subsequent reduction performed with zinc-modified NaBH3CN at room temperature cyclic amines can be isolated in good yields.
- Bytschkov, Igor,Doye, Sven
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p. 3715 - 3718
(2007/10/03)
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- Ruthenium-catalyzed intramolecular hydroamination of aminoalkynes
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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)
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- Carbon-to-Nitrogen Rearrangement in N-(Arylsulfonoxy)amines as a Route to Azacyclic Compounds
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A series of cyclic amines 1-10 was converted to the N-((p-nitrophenyl)sulfonoxy)amine derivatives with (p-nitrophenyl)sulfonyl peroxide.These compounds rearranged to ring-expanded cyclic imines in fair to good yields.Conversion of the amine to its hydroxy
- Hoffman, Robert V.,Buntain, Gregory A.
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p. 3316 - 3321
(2007/10/02)
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- α-Amino Carbanions. Preparation, Metalation, and Alkylation of Enamidines. Synthesis of Piperidine and Pyrrolidine Natural Products and Homologation of Carbonyl Compounds
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Saturated heterocycles, as their tert-butylformamidines, may be transformed into enamidines, by metalation-selenation-elimination.These enamidines are valuable precursors to 2-substituted, 2,4-disubstituted, and 2,4,6-trisubstituted pyrrolidines, piperidines, and perhydroazepines, prepared in a regiospecific manner.The method is demonstrated by the synthsesis of selenopsin A and the red fire ant venom.The use of acyclic enamidines is displayed as a homologation reagent which converts carbonyl compounds to higher alkyl derivatives.
- Meyers, A. I.,Edwards, Philip D.,Bailey, Thomas R.,Jagdmann, G. Erik
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p. 1019 - 1026
(2007/10/02)
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