- Triethyl Phosphite/Benzoyl Peroxide Mediated Reductive Dealkylation of O-Benzoylhydroxylamines: A Cascade Synthesis of Secondary Amides
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A new triethyl phosphite/benzoyl peroxide (BPO) mediated system has been developed for the synthesis of secondary amides with good to excellent yields in a single step. This unprecedented cascade process involves sequential reduction of N–O bond and benzoylation followed by dealkylation of N–C bond of O-benzoylhydroxylamines (O-BHA). The methodology is versatile as it tolerates a variety of aromatic and aliphatic O-BHA as substrates to access secondary amides.
- Aegurla, Balakrishna,Mandle, Ram D.,Shinde, Prasad G.,Parit, Ratan S.,Kamble, Sanjay P.,Sudalai, Arumugam,Senthilkumar, Beeran
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supporting information
p. 4235 - 4238
(2020/07/04)
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- Late Stage Functionalization of Secondary Amines via a Cobalt-Catalyzed Electrophilic Amination of Organozinc Reagents
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A general preparation of polyfunctional hydroxylamine benzoates from the corresponding secondary amines is reported. This convenient synthesis allows the setup of a late-stage functionalization of various secondary amines, including pharmaceuticals and peptidic derivatives. Thus, a cross-coupling of hydroxylamine benzoates with various alkyl-, aryl-, and heteroaryl-zinc chlorides in the presence of 5 mol % CoCl2 (25 °C, 2 h) provides a range of polyfunctional tertiary amines. This method was used to prepare penfluridol and gepirone.
- Gra?l, Simon,Chen, Yi-Hung,Hamze, Clémence,Tüllmann, Carl Phillip,Knochel, Paul
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p. 494 - 497
(2019/01/14)
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- Direct N-O bond formation via oxidation of amines with benzoyl peroxide
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Herein, we report a general and efficient method for direct N-O bond formation without undesirable C-N bond (amide) formation starting from commercially available amines and benzoyl peroxide. The oxidation of 1,2-diamines to furnish bis-(benzoyloxy)-1,2-diamines is reported for the first time. We found that a significant amount of water (BPO?:?water = 3?:?1) in combination with Cs2CO3 is necessary to achieve high selectivity and yield. The reaction conditions are applicable to a wide range of 1,2-diamine and 1,2-disubstituted-1,2-diamine substrates. Additionally this method is highly applicable to primary and secondary amines. Further, the present method can access chiral bis-hydroxamic acids and bis-hydroxyl amines in just two steps from 1,2-diamines. The reaction conditions are simple, mild and inert atmosphere free. The synthetic potential of this methodology is further demonstrated in the short synthesis of a chiral BHA ligand.
- Banerjee, Amit,Yamamoto, Hisashi
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p. 2124 - 2129
(2019/02/20)
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- Copper-Catalyzed Three-Component Carboamination of Arynes: Expeditious Synthesis of o-Alkynyl Anilines and o-Benzoxazolyl Anilines
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A copper-catalyzed three-component reaction of in situ formed arynes, terminal alkynes, and O-benzoylhydroxylamines has been developed. By adjusting reaction conditions, the nucleophiles in this transformation can be extended from terminal alkynes to benzoxazoles. These procedures provide a modular and facile approach to o-alkynyl anilines and o-benzoxazolyl anilines from easily available substrates in only one step.
- Niu, Sheng-Li,Hu, Jiangtao,He, Kuicheng,Chen, Ying-Chun,Xiao, Qing
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supporting information
p. 4250 - 4254
(2019/06/07)
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- Copper-Catalyzed Electrophilic Ortho C(sp2)-H Amination of Aryl Amines: Dramatic Reactivity of Bicyclic System
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A practical copper-catalyzed, 2-picolinamide-directed ortho C-H amination of anilines with benzoyl-protected hydroxylamines has been disclosed that proceeds smoothly without any external stoichiometric oxidant or additives. Remarkably, besides anilines, b
- Begam, Hasina Mamataj,Choudhury, Rajarshee,Behera, Ashok,Jana, Ranjan
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supporting information
p. 4651 - 4656
(2019/06/17)
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- Enantioselective Synthesis of 4-Aminotetrahydroquinolines via 1,2-Reductive Dearomatization of Quinolines and Copper(I) Hydride-Catalyzed Asymmetric Hydroamination
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A 1,2-reductive dearomatization of quinolines and copper(II) acetate monohydrate/(R,R)-Ph-BPE/P(p-tolyl)3-catalyzed enantioselective hydroamination sequence was developed, affording diverse 4-amino-1,2,3,4-tetrahydroquinolines with high levels of enantioselectivity in either a stepwise or one-pot fashion. Pleasingly, internal cis-cyclic alkenes, which are challenging substrates in copper hydride-catalyzed enantioselective hydroamination reactions, were transformed efficiently under mild conditions.
- Xu-Xu, Qing-Feng,Zhang, Xiao,You, Shu-Li
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p. 5357 - 5362
(2019/09/06)
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- Mechanistically Guided Design of Ligands That Significantly Improve the Efficiency of CuH-Catalyzed Hydroamination Reactions
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Using a mechanically guided ligand design approach, a new ligand (SEGFAST) for the CuH-catalyzed hydroamination reaction of unactivated terminal olefins has been developed, providing a 62-fold rate increase over reactions compared to DTBM-SEGPHOS, the previous optimal ligand. Combining the respective strengths of computational chemistry and experimental kinetic measurements, we were able to quickly identify potential modifications that lead to more effective ligands, thus avoiding synthesizing and testing a large library of ligands. By optimizing the combination of attractive, noncovalent ligand-substrate interactions and the stability of the catalyst under the reaction conditions, we were able to identify a finely tuned hybrid ligand that greatly enables accelerated hydrocupration rates with unactivated alkenes. Moreover, a modular and robust synthetic sequence was devised, which allowed for the practical, gram-scale synthesis of these novel hybrid ligand structures.
- Thomas, Andy A.,Speck, Klaus,Kevlishvili, Ilia,Lu, Zhaohong,Liu, Peng,Buchwald, Stephen L.
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supporting information
p. 13976 - 13984
(2018/10/25)
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- Synthesis of N,N,O-Trisubstituted Hydroxylamines by Stepwise Reduction and Substitution of O-Acyl N,N-Disubstituted Hydroxylamines
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Diverse N,N,O-trisubstituted hydroxylamines, an under-represented group in compound collections, are readily prepared by partial reduction of N-acyloxy secondary amines with diisobutylaluminum hydride followed by acetylation and reduction of the so-formed O-acyl-N,N-disubstituted hydroxylamines with triethylsilane and boron trifluoride etherate. Use of carbon nucleophiles in the last step, including allyltributylstannane, silyl enol ethers, and 2-methylfuran, gives N,N,O-trisubstituted hydroxylamines with branching α- to the O-substituent. N,N-Disubstiuted hydroxylamines are conveniently prepared by reaction of secondary amines with dibenzoyl peroxide followed by diisobutylaluminum hydride reduction.
- Dhanju, Sandeep,Crich, David
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supporting information
p. 1820 - 1823
(2016/05/19)
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- Palladium-Catalyzed Norbornene-Mediated Tandem Amination/Cyanation Reaction: A Method for the Synthesis of ortho-Aminated Benzonitriles
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A palladium-catalyzed, norbornene-mediated tandem amination/cyanation reaction via Catellani-type C-H functionalization was developed using N-benzoyloxyamines as the amination reagent and Zn(CN)2 as the terminating agent. This transformation, in which one C-N bond and one C-C bond are formed, provides an efficient approach for the synthesis of ortho-aminated benzonitriles in one pot from easily accessible starting materials.
- Luo, Bo,Gao, Jin-Ming,Lautens, Mark
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supporting information
p. 4166 - 4169
(2016/10/12)
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- Copper(I)-Catalyzed Interrupted Click Reaction: Synthesis of Diverse 5-Hetero-Functionalized Triazoles
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The 5-heterofunctionalized triazoles are important scaffolds in bioactive compounds, but current click reactions (CuAAC) cannot produce these core structures. A copper(I)-catalyzed interrupted click reaction to access diverse 5-functionalized triazoles is reported. Various 5-amino-, thio-, and selenotriazoles were readily assembled in one step in high yields. The reaction proceeds under mild conditions with complete regioselectivity. It also features a broad substrate scope and good functional group compatibility.
- Wang, Weiguo,Peng, Xianglong,Wei, Fang,Tung, Chen-Ho,Xu, Zhenghu
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supporting information
p. 649 - 653
(2016/02/27)
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- Copper-catalyzed oxyamination of electron-deficient alkenes with N-acyloxyamines
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A Cu(i)-catalyzed direct intermolecular oxyamination of electron deficient alkenes is disclosed. This process is characterized by difunctionalization of a variety of α,β-unsaturated ketones with easily available N-acyloxyamine reagents as both amine and oxygen donors, which delivers ester derivatives of β-amino alcohols in good yields as well as with high regioselectivity. Control studies suggested the involvement of alkyl radical species on the way of product formation.
- Ren, Shichao,Song, Shengjin,Ye, Lu,Feng, Chao,Loh, Teck-Peng
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supporting information
p. 10373 - 10376
(2016/09/02)
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- Copper-catalyzed enantioselective formal hydroamination of oxa- and azabicyclic alkenes with hydrosilanes and hydroxylamines
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A CuCl/(R,R)-Ph-BPE-catalyzed enantioselective formal hydroamination of oxa- and azabicyclic alkenes with polymethylhydrosiloxane (PMHS) and O-benzoylhydroxylamines has been developed. The efficient and stereoselective net addition of hydrogen and nitrogen atoms provides the corresponding optically active oxa- and azanorbornenyl- and -norbornanylamines in good yields and good enantiomeric ratios.
- Miki, Yuya,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
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supporting information
p. 1498 - 1501
(2014/04/03)
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- Enantioselective CuH-catalyzed anti-markovnikov hydroamination of 1,1-disubstituted alkenes
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Enantioselective synthesis of β-chiral amines has been achieved via copper-catalyzed hydroamination of 1,1-disubstituted alkenes with hydroxylamine esters in the presence of a hydrosilane. This mild process affords a range of structurally diverse β-chiral amines, including β-deuterated amines, in excellent yields with high enantioselectivities. Furthermore, catalyst loading as low as 0.4 mol% could be employed to deliver product in undiminished yield and selectivity, demonstrating the practicality of this method for large-scale synthesis.
- Zhu, Shaolin,Buchwald, Stephen L.
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supporting information
p. 15913 - 15916
(2015/02/19)
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- Transition-metal-free electrophilic amination of arylboroxines
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A transition-metal-free strategy to construct C(sp2)-N bonds using arylboroxines and O-benzoyl hydroxylamines as coupling partners has been developed. This transformation provides a useful method to access various aromatic amines.
- Xiao, Qing,Tian, Leiming,Tan, Renchang,Xia, Ying,Qiu, Di,Zhang, Yan,Wang, Jianbo
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supporting information; experimental part
p. 4230 - 4233
(2012/09/22)
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- Copper-catalyzed electrophilic amination of organozinc nucleophiles: Documentation of O-benzoyl hydroxylamines as broadly useful R2N(+) and RHN(+) synthons
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This paper details new copper-catalyzed electrophilic amination reactions of diorganozinc reagents using O-benzoyl hydroxylamines as electrophilic nitrogen sources that may be accessed in one step. Simple and functionalized aryl, heteroaryl-, benzyl, n-alkyl, sec-alkyl, and tert-alkyl nucleophiles couple with R2NOC(O)Ph and RHNOC(O)Ph reagents in the presence of catalytic quantities of copper salts to provide tertiary and secondary amines, respectively, in generally good yields. In many cases, the product may be isolated analytically pure after a simple extractive workup. The amination process is shown to tolerate a significant degree of steric demand. The amination of nominally unreactive Caryl-H bonds via a sequential directed ortho metalation/transmetalation/catalytic amination reaction sequence is detailed. The direct Cu-catalyzed amination of Grignard reagents using cocatalysis by ZnCl2 is described.
- Herman, Ashley M.,Johnson, Jeffrey S.
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p. 219 - 224
(2007/10/03)
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- Copper-Catalyzed Electrophilic Amination of Diorganozinc Reagents
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The copper-catalyzed electrophilic amination of diorganozinc reagents employing O-acyl N,N-dialkyl hydroxylamine derivatives as aminating agents is described. This reaction offers a general method for the preparation of tertiary amines in high yields and is noteworthy for its convenience both in terms of reaction conditions employed (room temperature, ≤1 h) and ease of product isolation (acid/base extractive workup). Copyright
- Berman, Ashley M.,Johnson, Jeffrey S.
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p. 5680 - 5681
(2007/10/03)
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- Asymmetric synthesis of β-amino acids by addition of chiral enolates to nitrones via N-acyloxyiminium ions
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N-Acyloxyiminium ions, generated by the reaction of nitrones with acyl halides, are highly reactive species and undergo facile reaction with a wide range of nucleophiles, such as ketene silyl acetals, titanium(IV) and boron enolates, hydrido- and allyltin(IV) reagents, and alkynyltitanium(IV) reagents, to give α-substituted amine derivatives. Optically active β-amino acids can be prepared by the reaction of N-acyloxyiminium ions with both boron and titanium(IV) enolates bearing chiral auxiliaries. Reversal of diastereoselectivity was observed by the reactions of the boron and titanium(IV) enolates. Using these reactions, all of the four stereoisomers of α-methyl-β-phenylalanines, for example, can be prepared highly diastereoselectively. Cyclic N-acyloxyiminium ions are useful for the asymmetric synthesis of pyrrolidine and piperidine alkaloids; (5R,8R,8aS)-5-cyano-8-methylindolizidine, which is a common key intermediate for synthesis of 5-substituted 8-methylindolizidines, was prepared selectively.
- Kawakami,Ohtake,Arakawa,Okachi,Imada,Murahashi
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p. 2423 - 2444
(2007/10/03)
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