- Aminomethylation of Aryl Bromides by Nickel-Catalyzed Electrochemical Redox Neutral Cross Coupling
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We develop an electrochemical nickel-catalyzed aminomethylation of aryl bromides under mild conditions. The convergent paired electrolysis makes full use of anode and cathode processes, free of a terminal oxidant, a sacrificial anode, a metal reductant, and a prefunctionalized radical precursor. In addition, this method exhibits wide functional group tolerance (63 examples), including some sensitive substituents and aromatic heterocycles. This redox neutral cross coupling provides a more environmentally friendly and synthetic practical protocol for forging C(sp2)–C(sp3) bonds.
- Ma, Yueyue,Hong, Jufei,Yao, Xiantong,Liu, Chengyu,Zhang, Ling,Fu, Youtian,Sun, Maolin,Cheng, Ruihua,Li, Zhong,Ye, Jinxing
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supporting information
p. 9387 - 9392
(2021/12/17)
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- Borane-Trimethylamine Complex as a Reducing Agent for Selective Methylation and Formylation of Amines with CO2
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We report herein that a borane-trimethylamine complex worked as an efficient reducing agent for the selective methylation and formylation of amines with 1 atm CO2 under metal-free conditions. 6-Amino-2-picoline serves as a highly efficient catalyst for the methylation of various secondary amines, whereas in its absence, the formylation of primary and secondary amines was achieved in high yield with high chemoselectivity. Mechanistic studies suggest that the 6-amino-2-picoline-borane catalytic system operates like an intramolecular frustrated Lewis pair to activate CO2.
- Zhang, Yanmeng,Zhang, He,Gao, Ke
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supporting information
p. 8282 - 8286
(2021/10/25)
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- Mesoionic N-heterocyclic olefin catalysed reductive functionalization of CO2for consecutiveN-methylation of amines
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A mesoionic N-heterocyclic olefin (mNHO) was introduced as a metal-free catalyst for the reductive functionalization of CO2leading to consecutive doubleN-methylation of primary amines in the presence of 9-borabicyclo[3.3.1]nonane (9-BBN). A wide range of secondary amines and primary amines were successfully methylated under mild conditions. The catalyst sustained over six successive cycles ofN-methylation of secondary amines without compromising its activity, which encouraged us to check its efficacy towards doubleN-methylation of primary amines. Moreover, this method was utilized for the synthesis of two commercially available drug molecules. A detailed mechanistic cycle was proposed by performing a series of control reactions along with the successful characterisation of active catalytic intermediates either by single-crystal X-ray study or by NMR spectroscopic studies in association with DFT calculations.
- Das, Arpan,Maji, Subir,Mandal, Swadhin K.
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p. 12174 - 12180
(2021/09/28)
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- Synthesis of Quinolinium Salts from N-Substituted Anilines, Aldehydes, Alkynes, and Acids: Theoretical Understanding of the Mechanism and Regioselectivity
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Secondary anilines were first utilized in the four-component coupling of aniline, aldehyde, alkyne, and acid to synthesize a variety of N-substituted quinolinium salts. This method was carried out under mild reaction conditions and exhibited excellent chemo- and regioselectivities. DFT calculation was performed to analyze the cyclization step, where the interaction/distortion model provided better insight into the singular selectivity of terminal/internal alkynes in reaction.
- Chao, Tzu-Hsuan,Chen, Wei-Chen,Cheng, Chien-Hong,Cheng, Lin-Chieh,Cheng, Mu-Jeng,Santhoshkumar, Rajagopal
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supporting information
p. 2116 - 2129
(2020/04/23)
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- Endergonic addition of N -methylamines to aromatic ketones driven by photochemical offset of the entropic cost
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Intermolecular addition reactions are generally accompanied by an entropic penalty due to the decrease of molecular numbers during the reaction, which sometimes makes the reaction endergonic. Here we demonstrate that such an endergonic reaction can be promoted with light-energy as a driving force; N-methylamines were added to aromatic ketones to produce aminoalcohols under UV-light irradiation. The reaction represents an obvious example showing that the photochemical approach is effective to offset such an entropic cost, and thereby to drive thermodynamically uphill addition reactions. Moreover the present reactions are highly expedient from the synthetic view point, being transition-metal-catalyst-free, scalable, highly atom economical, and regioselective. The product amines can be converted in one step to functional multi-arylated enamines, which are potentially valuable compounds in electronic materials.
- Iwamoto, Takahiro,Hosokawa, Atsushi,Nakamura, Masaharu
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supporting information
p. 11683 - 11686
(2019/10/02)
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- DBU-Catalyzed Selective N-Methylation and N-Formylation of Amines with CO2 and Polymethylhydrosiloxane
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We describe herein an efficient organocatalytic system for the selective N-methylation and N-formylation of amines with carbon dioxide (CO2) as a sustainable C1 feedstock and polymethylhydrosiloxane (PMHS) as a cost-effectvie reducing reagent. High-yielding N-methylation products are obtained with low catalyst loading (1%) of DBU. Selective N-formylation of amines is achieved using the same catalytic system at a lower reaction temperature. (Figure presented.).
- Li, Gang,Chen, Jie,Zhu, Dao-Yong,Chen, Ye,Xia, Ji-Bao
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supporting information
p. 2364 - 2369
(2018/05/07)
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- Asymmetric Radical-Radical Cross-Coupling through Visible-Light-Activated Iridium Catalysis
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Combining single electron transfer between a donor substrate and a catalyst-activated acceptor substrate with a stereocontrolled radical-radical recombination enables the visible-light-driven catalytic enantio- and diastereoselective synthesis of 1,2-amino alcohols from trifluoromethyl ketones and tertiary amines. With a chiral iridium complex acting as both a Lewis acid and a photoredox catalyst, enantioselectivities of up to 99% ee were achieved. A quantum yield of 1 supports the proposed catalytic cycle in which at least one photon is needed for each asymmetric C-C bond formation mediated by single electron transfer.
- Wang, Chuanyong,Qin, Jie,Shen, Xiaodong,Riedel, Radostan,Harms, Klaus,Meggers, Eric
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supporting information
p. 685 - 688
(2016/02/23)
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- Early main group metal catalysis: How important is the metal?
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Organocalcium compounds have been reported as efficient catalysts for various alkene transformations. In contrast to transition metal catalysis, the alkenes are not activated by metal-alkene orbital interactions. Instead it is proposed that alkene activation proceeds through an electrostatic interaction with a Lewis acidic Ca2+. The role of the metal was evaluated by a study using the metal-free catalysts: [Ph2N-Me4N+] and [Ph3C-][Me4N- ]. These "naked" amides and carbanions can act as catalysts in the conversion of activated double bonds (C=O and C=N) in the hydroamination of Ar-N=C=O and R-N=C=N=R (R=alkyl) by Ph2NH. For the intramolecular hydroamination of unactivated C=C bonds in H2C=CHCH2CPh2CH2NH2 the presence of a metal cation is crucial. A new type of hybrid catalyst consisting of a strong organic Schwesinger base and a simple metal salt can act as catalyst for the intramolecular alkene hydroamination. The influence of the cation in catalysis is further evaluated by a DFT study.
- Harder, Sjoerd,Penafiel, Johanne,Maron, Laurent
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supporting information
p. 201 - 206
(2015/09/08)
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- Reductive amination of tertiary anilines and aldehydes
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An unprecedented oxidant-mediated reductive amination of tertiary anilines and aldehydes without external reducing agents was developed via the nucleophilic attack of the oxygen atom of the carbonyl group to in situ generated iminium ions, in which tertiary anilines were used as both nitrogen source and reducing agent for the first time. The Royal Society of Chemistry 2013.
- Lv, Yunhe,Zheng, Yiying,Li, Yan,Xiong, Tao,Zhang, Jingping,Liu, Qun,Zhang, Qian
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supporting information
p. 8866 - 8868
(2013/09/24)
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- Metal-free catalytic olefin hydrogenation: Low-temperature H2 activation by frustrated lewis pairs
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Weak nucleophiles for strong activation: The reversible activation of dihydrogen by an electron-deficient phosphine, (C6F 5)PPh2, in combination with the Lewis acid B(C 6F5)3 at -80 °C was accomplished. The catalytic hydrogenation of olefins proceeds through protonation and subsequent hydride attack. Electron-deficient phosphines and diarlyamines were demonstrated to be viable Lewis bases for the reaction, thus allowing catalyst loadings of 10 to 5 mol %. Copyright
- Greb, Lutz,Paradies, Jan,Ona-Burgos, Pascual,Schirmer, Birgitta,Grimme, Stefan,Stephan, Douglas W.
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supporting information
p. 10164 - 10168,5
(2020/09/09)
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