204059-95-0Relevant academic research and scientific papers
Mediator-Enabled Electrocatalysis with Ligandless Copper for Anaerobic Chan-Lam Coupling Reactions
Walker, Benjamin R.,Manabe, Shuhei,Brusoe, Andrew T.,Sevov, Christo S.
supporting information, p. 6257 - 6265 (2021/05/07)
Simple copper salts serve as catalysts to effect C-X bond-forming reactions in some of the most utilized transformations in synthesis, including the oxidative coupling of aryl boronic acids and amines. However, these Chan-Lam coupling reactions have historically relied on chemical oxidants that limit their applicability beyond small-scale synthesis. Despite the success of replacing strong chemical oxidants with electrochemistry for a variety of metal-catalyzed processes, electrooxidative reactions with ligandless copper catalysts are plagued by slow electron-transfer kinetics, irreversible copper plating, and competitive substrate oxidation. Herein, we report the implementation of substoichiometric quantities of redox mediators to address limitations to Cu-catalyzed electrosynthesis. Mechanistic studies reveal that mediators serve multiple roles by (i) rapidly oxidizing low-valent Cu intermediates, (ii) stripping Cu metal from the cathode to regenerate the catalyst and reveal the active Pt surface for proton reduction, and (iii) providing anodic overcharge protection to prevent substrate oxidation. This strategy is applied to Chan-Lam coupling of aryl-, heteroaryl-, and alkylamines with arylboronic acids in the absence of chemical oxidants. Couplings under these electrochemical conditions occur with higher yields and shorter reaction times than conventional reactions in air and provide complementary substrate reactivity.
Direct Aryl C?H Amination with Primary Amines Using Organic Photoredox Catalysis
Margrey, Kaila A.,Levens, Alison,Nicewicz, David A.
supporting information, p. 15644 - 15648 (2017/11/20)
The direct catalytic C?H amination of arenes is a powerful synthetic strategy with useful applications in pharmaceuticals, agrochemicals, and materials chemistry. Despite the advances in catalytic C?H functionalization, the use of aliphatic amine coupling partners is limited. Described herein is the construction of C?N bonds, using primary amines, by direct C?H functionalization with an acridinium photoredox catalyst under an aerobic atmosphere. A wide variety of primary amines, including amino acids and more complex amines are competent coupling partners. Various electron-rich aromatics and heteroaromatics are useful scaffolds in this reaction, as are complex, biologically active arenes. We also describe the ability to functionalize arenes that are not oxidized by an acridinium catalyst, such as benzene and toluene, thus supporting a reactive amine cation radical intermediate.
Room temperature N-arylation of amino acids and peptides using copper(i) and β-diketone
Sharma, Krishna K.,Sharma, Swagat,Kudwal, Anurag,Jain, Rahul
supporting information, p. 4637 - 4641 (2015/04/27)
A mild and efficient method for the N-arylation of zwitterionic amino acids, amino acid esters and peptides is described. The procedure provides the first room temperature synthesis of N-arylated amino acids and peptides using CuI as a catalyst, diketone as a ligand, and aryl iodides as coupling partners. The method is equally applicable for using relatively inexpensive aryl bromides as coupling partners at 80 °C. Using this procedure, electronically and sterically diverse aryl halides, containing reactive functional groups were efficiently coupled in good to excellent yields.
Synthesis of enantiomerically enriched indolines and tetrahydroisoquinolines from (S)-amino acid-derived chiral carbocations: An easy access to (3S,4R)-demethoxy-3-isopropyl diclofensine
Manna, Sudipta Kumar,Panda, Gautam
, p. 8318 - 8324 (2015/01/09)
Enantiomerically enriched indolines and tetrahydroisoquinolines were synthesized within 5 min to 2 h in high yields from easily accessible (S)-amino acid derived chiral carbocations. The diastereoselective Friedel-Crafts reaction is promoted by a Lewis acid (AlCl3) offering trans-diastereoselectivity. The rate of the reaction and diastereoselectivity of the product are significantly influenced by steric hindrance of the amino acids substituents and aryl groups. The methodology can be applied for the synthesis of the enantiomerically enriched bioactive scaffold (3S,4R)-demethoxy-3-isopropyl diclofensine. This journal is
A mild and catalyst-free aromatization using dihydroxylcyclohexanone derivatives as phenyl sources: A new approach to anilines
Luo, Jun,Ji, Enwei,Ye, Jingyuan,Wu, Runze,Qiu, Lei
, p. 4505 - 4508 (2013/08/23)
A new and efficient protocol for the preparation of N-substituted anilines via an aromatization reaction was developed. 3,5-Dihydroxylcyclohexanone derivatives were used as the sources of the phenyl group and reacted smoothly with primary or secondary amines under mild conditions in the absence of metal catalyst and strong base. A variety of N-substituted anilines were prepared by this method with excellent yields up to 99%. The results indicate that this reaction begins with a nucleophilic addition.
Use of diphenyliodonium bromide in the synthesis of some N-phenyl-amino acids
McKerrow, Jason D.,Al-Rawi, Jasim M. A.,Brooks, Peter
experimental part, p. 1161 - 1179 (2010/04/28)
The N-phenyl methyl esters 4 of glycine, alanine, valine, leucine, isoleucine, phenylalanine, methionine, proline, serine, threonine, tyrosine, aspartic acid, and glutamic acid have been synthesized in good to excellent yields using diphenyliodonium bromide, AgNO3, and a catalytic amount of CuBr starting from the relevant amino acid ester. The chiral integrity of the amino acids 5 was maintained during these reactions, which were confirmed by the synthesis of dipeptide for each N-phenyl amino acid. The structures of the new compounds were confirmed by the analysis of their IR, 1H, and 13C NMR spectra in addition to CHN microanalysis or high-resolution mass spectrometry for the new N-phenyl amino acids 5 and the esters 4.
Concepts for ligand design in asymmetric catalysis: A study of chiral amino thiol ligands
Anderson, James C.,Cubbon, Rachel,Harding, Michael,James, Daniel S.
, p. 3461 - 3490 (2007/10/03)
A series of new chiral sulfur-nitrogen chelate ligands, derived from amino acids, has been synthesised rationally. Fruitless experiments into catalytic asymmetric conjugate additions and desymmetrisation of meso- epoxides led us to analyse our ligands in
The importance of nitrogen substituents in chiral amino thiol ligands for the asymmetric addition of diethylzinc to aromatic aldehydes
Anderson, James C.,Harding, Michael
, p. 393 - 394 (2007/10/03)
A new series of N,S-chelate ligands derived from (S)-valine, which possess the capability of a stereogenic nitrogen donor atom, are catalysts for the addition of diethylzinc to aromatic aldehydes and gave the product secondary alcohols in up to 82% ee.
