- Electrochemical Activation of Diverse Conventional Photoredox Catalysts Induces Potent Photoreductant Activity**
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Herein, we disclose that electrochemical stimulation induces new photocatalytic activity from a range of structurally diverse conventional photocatalysts. These studies uncover a new electron-primed photoredox catalyst capable of promoting the reductive cleavage of strong C(sp2)?N and C(sp2)?O bonds. We illustrate several examples of the synthetic utility of these deeply reducing but otherwise safe and mild catalytic conditions. Finally, we employ electrochemical current measurements to perform a reaction progress kinetic analysis. This technique reveals that the improved activity of this new system is a consequence of an enhanced catalyst stability profile.
- Chernowsky, Colleen P.,Chmiel, Alyah F.,Wickens, Zachary K.
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supporting information
p. 21418 - 21425
(2021/08/25)
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- N?N Bond Formation Using an Iodonitrene as an Umpolung of Ammonia: Straightforward and Chemoselective Synthesis of Hydrazinium Salts
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The formation of hydrazinium salts by N?N bond formation has typically involved the use of hazardous and difficult to handle reagents. Here, mild and operationally simple conditions for the synthesis of hydrazinium salts are reported. Electrophilic nitrogen transfer to the nitrogen atom of tertiary amines is achieved using iodosylbenzene as oxidant and ammonium carbamate as the N-source. The resulting process is highly chemoselective and tolerant to other functional groups. A wide scope is reported, including examples with bioactive molecules. Insights on the structure of hydrazinium salts were provided by X-ray analysis. (Figure presented.).
- Tota, Arianna,Colella, Marco,Carlucci, Claudia,Aramini, Andrea,Clarkson, Guy,Degennaro, Leonardo,Bull, James A.,Luisi, Renzo
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supporting information
p. 194 - 199
(2020/10/28)
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- Thiourea-Catalyzed C?F Bond Activation: Amination of Benzylic Fluorides
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We describe the first thiourea-catalyzed C?F bond activation. The use of a thiourea catalyst and Ti(OiPr)4 as a fluoride scavenger allows the amination of benzylic fluorides to proceed in moderate to excellent yields. Preliminary results with S- and O-based nucleophiles are also presented. DFT calculations reveal the importance of hydrogen bonds between the catalyst and the fluorine atom of the substrate to lower the activation energy during the transition state.
- Houle, Camille,Savoie, Paul R.,Davies, Clotilde,Jardel, Damien,Champagne, Pier Alexandre,Bibal, Brigitte,Paquin, Jean-Fran?ois
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p. 10620 - 10625
(2020/07/24)
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- Photochemical benzylic bromination in continuous flow using BrCCl3 and its application to telescoped p-methoxybenzyl protection
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BrCCl3 represents a rarely used benzylic brominating reagent with complementary reactivity to other reagents. Its reactivity has been revisited in continuous flow, revealing compatibility with electron-rich aromatic substrates. This has brought about the development of a p-methoxybenzyl bromide generator for PMB protection, which was successfully demonstrated on a pharmaceutically relevant intermediate on 11 g scale, giving 91% yield and a PMB-Br space-time-yield of 1.27 kg L?1 h?1
- Otake, Yuma,Williams, Jason D.,Rincón, Juan A.,De Frutos, Oscar,Mateos, Carlos,Kappe, C. Oliver
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p. 1384 - 1388
(2019/02/14)
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- Base-promoted N-alkylation using formamides as the N-sources in neat water
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An efficient catalyst-free, alternative method for the C-N bond formation reaction of alkyl electrophiles using formamides as the N-sources was achieved under mild conditions. The reaction possesses the advantages of a broad range of substrates scope and wide functional group tolerance. It should also be noted that this process was performed using the environmentally benign water as the sole solvent, and high yield can also be achieved in ten-gram scale.
- Chen, Wen-Xin,Zhang, Cai-Yun,Shao, Li-Xiong
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p. 880 - 885
(2014/01/23)
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- Highly efficient amination in neat water of benzyl chlorides with dialkylformamides catalysed by N-heterocyclic carbene-palladium(II)-1- methylimidazole complex
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Dialkylformamides are excellent N-sources in the amination of benzyl chlorides when catalysed by a NHC-Pd(II)-Im complex. In the presence of NaOH and the catalyst, variously substituted benzyl chlorides and five different dialkylformamides reacted smoothly to afford the corresponding N,N-dialkyl-benzylamines in good to almost quantitative yields in eco-friendly solvent water at 50 °C within 3 h.
- Chen, Wen-Xin,Zhang, Cai-Yun,Lu, Jian-Mei
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p. 611 - 614
(2013/11/06)
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- 3-[(5-Chloro-2-hydroxyphenyl)methyl]-5-[4-(trifluoromethyl)phenyl]-1,3, 4-oxadiazol-2(3H)-one, BMS-191011: Opener of large-conductance Ca 2+-activated potassium (maxi-K) channels, identification, solubility, and SAR
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Compound 8a (BMS-191011), an opener of the cloned large-conductance, Ca2+-activated potassium (maxi-K) channel, demonstrated efficacy in in vivo stroke models, which led to its nomination as a candidate for clinical evaluation. Its maxi-K channel opening properties were consistent with its structural topology, being derived by combining elements from other known maxi-K openers. However, 8a suffered from poor aqueous solubility, which complicated elucidation of SAR during in vitro evaluation. The activity of 8a in in vivo stroke models and studies directed toward improving its solubility are reported herein. Enhanced solubility was achieved by appending heterocycles to the 8a scaffold, and a notable observation was made that inclusion of a simple amino group (anilines 8k and 8l) yielded excellent in vitro maxi-K ion channel opening activity and enhanced brain-to-plasma partitioning compared to the appended heterocycles.
- Romine, Jeffrey L.,Martin, Scott W.,Meanwell, Nicholas A.,Gribkoff, Valentin K.,Boissard, Christopher G.,Dworetzky, Steven I.,Natale, Joanne,Moon, Sandra,Ortiz, Astrid,Yeleswaram, Swamy,Pajor, Lorraine,Gao, Qi,Starrett Jr., John E.
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p. 528 - 542
(2007/10/03)
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- Reductive amination of aldehydes and ketones with sodium triacetoxyborohydride. Studies on direct and indirect reductive amination procedures
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Sodium triacetoxyborohydride is presented as a general reducing agent for the reductive amination of aldehydes and ketones. Procedures for using this mild and selective reagent have been developed for a wide variety of substrates. The scope of the reaction includes aliphatic acyclic and cyclic ketones, aliphatic and aromatic aldehydes, and primary and secondary amines including a variety of weakly basic and nonbasic amines. Limitations include reactions with aromatic and unsaturated ketones and some sterically hindered ketones and amines. 1,2-Dichloroethane (DCE) is the preferred reaction solvent, but reactions can also be carried out in tetrahydrofuran (THF) and occasionally in acetonitrile. Acetic acid may be used as catalyst with ketone reactions, but it is generally not needed with aldehydes. The procedure is carried out effectively in the presence of acid sensitive functional groups such as acetals and ketals; it can also be carried out in the presence of reducible functional groups such as C-C multiple bonds and cyano and nitro groups. Reactions are generally faster in DCE than in THF, and in both solvents, reactions are faster in the presence of AcOH. In comparison with other reductive amination procedures such as NaBH3CN/MeOH, borane-pyridine, and catalytic hydrogenation, NaBH(OAc)3 gave consistently higher yields and fewer side products. In the reductive amination of some aldehydes with primary amines where dialkylation is a problem we adopted a stepwise procedure involving imine formation in MeOH followed by reduction with NaBH4.
- Abdel-Magid, Ahmed F.,Carson, Kenneth G.,Harris, Bruce D.,Maryanoff, Cynthia A.,Shah, Rekha D.
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p. 3849 - 3862
(2007/10/03)
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- Reductive amination of aldehydes and ketones by using sodium triacetoxyborohydride
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Sodium triacetoxyborohydride is a reagent of choice in the reductive amination of aldehydes and saturated aliphatic ketones with primary and secondary amines.
- Abdel-Magid,Maryanoff,Carson
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p. 5595 - 5598
(2007/10/02)
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- MANNICH REACTIONS OF ARYLTRIALKYLSTANNANES IN APROTIC SOLVENTS
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Aryltributyl- and aryltrimethyl-stannanes react with a range of N,N-dialkylmethylene-imonium salts to afford N,N-dialkylaminomethyl derivatives in good yields.The method can be used to obtain regioisomers that are not available using classical procedures. "In situ" reactions can also be carried out using alkoxydialkylaminomethanes (aminol ethers) and bis(dialkylamino)methanes (aminals) together with chlorotrimethyl- and trichloromethyl-silanes as the source of the electrophile.However, the "in situ" reactions do not afford good yields in the majority of cases, as a result of the inhibition of imonium salt formation by trialkylchlorostannane.
- Cooper, Mark S.,Fairhurst, Robin A.,Heaney, Harry,Papageorgiou, George,Wilkins, Robert F.
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p. 1155 - 1166
(2007/10/02)
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