- B(C6F5)3-catalyzed tandem protonation/deuteration and reduction of: In situ -formed enamines
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A highly efficient B(C6F5)3-catalyzed tandem protonation/deuteration and reduction of in situ-formed enamines in the presence of water and pinacolborane was developed. Regioselective β-deuteration of tertiary amines was achieved with high chemo- and regioselectivity. D2O was used as a readily available and cheap source of deuterium. Mechanistic studies indicated that B(C6F5)3 could activate water to promote the protonation and reduction of enamines. This journal is
- Wu, Rongpei,Gao, Ke
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p. 4032 - 4036
(2021/05/19)
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- Synergistic Bimetallic Ni/Ag and Ni/Cu Catalysis for Regioselective γ,δ-Diarylation of Alkenyl Ketimines: Addressing β-H Elimination by in Situ Generation of Cationic Ni(II) Catalysts
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We disclose unprecedented synergistic bimetallic Ni/Ag and Ni/Cu catalysts for regioselective γ,δ-diarylation of unactivated alkenes in simple ketimines with aryl halides and arylzinc reagents. The bimetallic synergy, which generates cationic Ni(II) speci
- Basnet, Prakash,Kc, Shekhar,Dhungana, Roshan K.,Shrestha, Bijay,Boyle, Timothy J.,Giri, Ramesh
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supporting information
p. 15586 - 15590
(2018/11/23)
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- SmI2(H2O)n Reduction of Electron Rich Enamines by Proton-Coupled Electron Transfer
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Samarium diiodide in the presence of water and THF (SmI2(H2O)n) has in recent years become a versatile and useful reagent, mainly for reducing carbonyl-type substrates. This work reports the reduction of several enamines by SmI2(H2O)n. Mechanistic experiments implicate a concerted proton-coupled electron transfer (PCET) pathway, based on various pieces of evidence against initial outer-sphere electron transfer, proton transfer, or substrate coordination. A thermochemical analysis indicates that the C-H bond formed in the rate-determining step has a bond dissociation free energy (BDFE) of ~32 kcal mol-1. The O-H BDFE of the samarium aquo ion is estimated to be 26 kcal mol-1, which is among the weakest known X-H bonds of stable reagents. Thus, SmI2(H2O)n should be able to form very weak C-H bonds. The reduction of these highly electron rich substrates by SmI2(H2O)n shows that this reagent is a very strong hydrogen atom donor as well as an outer-sphere reductant.
- Kolmar, Scott S.,Mayer, James M.
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supporting information
p. 10687 - 10692
(2017/08/15)
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- Synthesis and Reactivity of Phosphine-Quinolinolato Rhodium Complexes: Intermediacy of Vinylidene and (Amino)carbene Complexes in the Catalytic Hydroamination of Terminal Alkynes
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We report here on the syntheses of rhodium(I) complexes bearing a phosphine-quinolinolate ligand and the isolation of two classes of important intermediates in the anti-Markovnikov hydroamination of terminal alkynes with secondary amines: vinylidene-bridged dirhodium complexes and (amino)carbene complexes. We first prepared various rhodium(I) complexes bearing a phosphine-quinolinolate ligand and found that some of these complexes had catalytic activity for the anti-Markovnikov hydroamination of terminal alkynes with secondary amines. The reaction of stoichiometric amounts of a (PNO)Rh complex with terminal alkynes provided vinylidene-bridged dirhodium complexes. When the resulting vinylidene complexes were reacted with secondary amines, (amino)carbene complexes were generated, which gave the hydroamination product upon heating with an additive. These results suggest that this anti-Markovnikov hydroamination catalyzed by (PNO)Rh complexes proceeds via vinylidene and (amino)carbene complexes.
- Takano, Shotaro,Kochi, Takuya,Kakiuchi, Fumitoshi
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p. 4112 - 4125
(2017/01/10)
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- Colloid and nanosized catalysts in organic synthesis: XIV. Reductive amination and amidation of carbonitriles catalyzed by nickel nanoparticles
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Hydrogenation of carbonitriles catalyzed by nickel nanoparticles in the presence of primary amines led to the predominant formation of unsymmetrical secondary amines. In the presence of secondary amines hydrogenation of nitrites provided enamines as main products. Hydrogenation of nitriles in the presence of formamide or acetamide afforded formyl or acetyl derivatives of primary amines.
- Popov, Yu. V.,Mokhov,Shcherbakova
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p. 798 - 805
(2016/06/13)
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- Mild and selective Et2Zn-catalyzed reduction of tertiary amides under Hydrosilylation conditions
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Diethylzinc (Et2Zn) can be used as an efficient and chemoselective catalyst for the reduction of tertiary amides under mild reaction conditions employing cost-effective polymeric silane (PMHS) as the hydride source. Crucial for the catalytic activity was the addition of a substoichiometric amount of lithium chloride to the reaction mixture. A series of amides containing different additional functional groups were reduced to their corresponding amines, and the products were isolated in good-to-excellent yields.
- Kovalenko, Oleksandr O.,Volkov, Alexey,Adolfsson, Hans
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supporting information
p. 446 - 449
(2015/03/05)
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- Dynamic kinetic resolution of racemic γ-aryl-δ-oxoesters. Enantioselective synthesis of 3-arylpiperidines
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Cyclodehydration of racemic γ-aryl-δ-oxoesters with (R)- or (S)-phenylglycinol stereoselectively affords bicyclic δ-lactams, in a process that involves a dynamic kinetic resolution. Subsequent reduction of these lactams leads to enantiopure 3-arylpiperidines. Starting from racemic aldehyde esters, this short sequence has been applied to the synthesis of (R)-3-phenylpiperidine and the antipsychotic drug (-)-3-PPP (an (S)-3-arylpiperidine), whereas starting from racemic ketone esters enantiopure cis-2-alkyl-3-arylpiperidines are prepared.
- Amat, Mercedes,Canto, Margalida,Llor, Nuria,Escolano, Carmen,Molins, Elies,Espinosa, Enrique,Bosch, Joan
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p. 5343 - 5351
(2007/10/03)
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- Novel Synthesis of 3,5-Disubstituted Pyridines by 1,4-Cycloaddition of 1-Aza-1,3-butadienes with Enamines
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A new method for the synthesis of 3,5-disubstituted pyridines is described.Reactions of the N-substituted methanimines 1 with the β-substituted enamines 2 give 1-aza-1,3-butadienes 3a-3i and/or symmetrically 3,5-disubstituted pyridines 4a-c,e-h in moderate to good yields.At reaction temperatures of 150 deg C the azadienes 3 are the predominant products, and the reaction provides a good route to 1-azadienes with no substituent at the 4-position.At reaction temperatures of 200 deg C, and particularly using N-tert-butylmethanimine 1a and p-toluenesulfonic acid catalyst, the principal products are symmetrically 3,5-disubstituted pyridines.The cycloaddition was shown to proceed via the azabutadiene intermediate 3.Reactions of 3 with the enamines 2 lead to unsymmetrically 3,5-disubstituted pyridines.The mechanisms of these cycloadditions are discussed.
- Komatsu, Mitsuo,Takamatsu, Shigeki,Uesaka, Masatoshi,Yamamoto, Shinji,Ohshiro, Yoshiki,Agawa, Toshio
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p. 2691 - 2699
(2007/10/02)
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