- Reductive Amination by Photoredox Catalysis and Polarity-Matched Hydrogen Atom Transfer
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The excitation of a RuII photosensitizer in the presence of ascorbic acid leads to the reduction of iminium ions to electron-rich α-aminoalkyl radical intermediates, which are rapidly converted into reductive amination products by thiol-mediated hydrogen atom transfer (HAT). As a result, the reductive amination of carbonyl compounds with amines by photoredox catalysis proceeds in good to excellent yields and with broad substrate scope and good functional group tolerance. The three key features of this work are 1) the rapid interception of electron-rich α-aminoalkyl radical intermediates by polarity-matched HAT in a photoredox reaction, 2) the method of reductive amination by photoredox catalysis itself, and 3) the application of this new method for temporally and spatially controlled reactions on a solid support, as demonstrated by the attachment of a fluorescent dye on an activated cellulose support by photoredox-catalyzed reductive amination.
- Guo, Xingwei,Wenger, Oliver S.
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supporting information
p. 2469 - 2473
(2018/01/27)
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- Carbon dioxide transformation in imidazolium salts: Hydroaminomethylation catalyzed by Ru-complexes
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The catalytic species generated by dissolving Ru3(CO)12 in the ionic liquids 1-n-butyl-3-methyl-imidazolium chloride or 1-n-butyl-2,3-dimethyl-imidazolium chloride are efficient multifunctional catalysts for: (a) reverse water-gas shift, (b) hydroformylation of alkenes, and (c) reductive amination of aldehydes. Thus the reaction of alkenes with primary or secondary amines (alkene/amine, 1:1) under CO2/H2 (1:1) affords the hydroamino-methylations products in high alkene conversions (up to 99%) and selectivities (up to 96%). The reaction proceeds under relatively mild reaction conditions (120 °C, 60 bar = 6 MPa) and affords selectively secondary and tertiary amines. The presence of amine strongly reduces the alkene hydrogenation competitive pathway usually observed in the hydroformylation of terminal alkenes by Ru complexes. The catalytic system is also highly active for the reductive amination of aldehydes and ketones yielding amines in high yields (> 90%).
- Ali, Meher,Gual, Aitor,Ebeling, Gunter,Dupont, Jairton
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p. 2129 - 2134
(2017/07/25)
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- Controlled Reduction of Tertiary Amides to the Corresponding Alcohols, Aldehydes, or Amines Using Dialkylboranes and Aminoborohydride Reagents
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Dialkylboranes and aminoborohydrides are mild, selective reducing agents complementary to the commonly utilized amide reducing agents, such as lithium aluminum hydride (LiAlH4) and diisobutylaluminum hydride (DIBAL) reagents. Tertiary amides were reduced using 1 or 2 equiv of various dialkylboranes. The reduction of tertiary amides required 2 equiv of 9-borabicyclo[3.3.1]nonane (9-BBN) for complete reduction to give the corresponding tertiary amines. One equivalent of sterically hindered disiamylborane reacts with tertiary amides to afford the corresponding aldehydes. Aminoborohydrides are powerful and selective reducing agents for the reduction of tertiary amides. Lithium dimethylaminoborohydride and lithium diisopropylaminoborohydride are prepared from n-butyllithium and the corresponding amine-borane. Chloromagnesium dimethylaminoborohydride (ClMg+[H3B-NMe2]-, MgAB) is prepared by the reaction of dimethylamine-borane with methylmagnesium chloride. Solutions of aminoborohydride reduce aliphatic, aromatic, and heteroaromatic tertiary amides to give the corresponding alcohol, amine, or aldehyde depending on the steric requirement of the tertiary amide and the aminoborohydride used.
- Bailey, Christopher L.,Joh, Alexander Y.,Hurley, Zefan Q.,Anderson, Christopher L.,Singaram, Bakthan
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p. 3619 - 3628
(2016/05/24)
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- Iridium-catalyzed decarboxylative N-alkylation of α-amino acids with primary alcohols
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A new decarboxylative N-alkylation reaction of α-amino acids has been developed. A variety of tertiary amines were obtained in good to excellent yields via the decarboxylative N-alkylation reaction of α-amino acids with primary alcohols catalyzed by a CpIr complex. Georg Thieme Verlag Stuttgart New York.
- Wu, Jiashou,Jiang, Huajiang,Chen, Dingben,Shen, Jianfen,Zhao, Datong,Xiang, Jing,Zhou, Qizhong
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p. 539 - 542
(2014/03/21)
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- 7-Azabicyclo[2.2.1]heptane as a scaffold for the development of selective sigma-2 (σ2) receptor ligands
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A series of N-substituted 7-azabicyclo[2.2.1]heptanes (12-17 and 22-25) and similarly substituted pyrrolidines (32-36 and 41-44) were synthesized as sterically-reduced, achiral analogs of adamantane- and trishomocubane-derived σ ligands. In vitro competition binding assays against σ receptors revealed that arylalkyl N-substituents conferred selectivity for the σ2 subtype, while alicyclic or polycarbocyclic substituents imparted high affinity for both subtypes. The σ2 binding and subtype selectivities of N-arylalkyl-7-azanorbornanes was generally greater than the analogously-substituted pyrrolidines, indicating that steric bulk and conformational restriction around the nitrogen atom are likely important for subtype discrimination.
- Banister, Samuel D.,Rendina, Louis M.,Kassiou, Michael
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supporting information; experimental part
p. 4059 - 4063
(2012/07/03)
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- Controlled reduction of tertiary amides to the corresponding aldehydes or amines using dialkylboranes
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Several tertiary amides were reduced using one or two equivalents of various dialkylboranes, such as 9-borabicyclo[3.3.1] nonane (9-BBN), dicyclohexylborane (Chx2BH), or disiamylborane (Sia2BH). The reduction of tertiary amides having alkyl substituents of varying steric requirement at the nitrogen atom, required two equivalents of 9-BBN for complete reduction and gave the corresponding tertiary amines. However, sterically more hindered dialkylboranes such as Chx2BH and Sia2BH, reacted in 1:1 stoichiometry with tertiary amides and partially reduced them to the corresponding aldehydes.
- Godjoian, Gayane,Singaram, Bakthan
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p. 1717 - 1720
(2007/10/03)
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- Scope and Pathway of Catalytic Aminomethylation of Olefins
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We describe a general and high-yield one-step process for synthesis of tertiary and secondary amines from olefins, carbon monoxide, water, and a nitrogen source in the presence of transition-metal compounds as catalysts.We find this chemistry, initially d
- Jachimowicz, Felek,Raksis, Joseph W.
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p. 445 - 447
(2007/10/02)
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- Preparation of amines
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Amines are prepared by reacting ammonia, a primary amine or a secondary amine with an olefin, carbon monoxide and water in the presence of a rhodium catalyst which is rhodium oxide or a rhodium compound capable of forming a rhodium carbonyl and iron carbonyl.
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