1
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Zhu L, Zhao B, Xie K, Gui WT, Niu SL, Zheng PF, Chen YC, Qi XW, Ouyang Q. Metal π-Lewis base activation in palladium(0)-catalyzed trans-alkylative cyclization of alkynals. Chem Sci 2024; 15:13032-13040. [PMID: 39148807 PMCID: PMC11323327 DOI: 10.1039/d4sc04190a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2024] [Accepted: 07/12/2024] [Indexed: 08/17/2024] Open
Abstract
The Pd(0)-mediated umpolung reaction of an alkyne to achieve trans-difunctionalization is a potential synthetic methodology, but its insightful activation mechanism of Pd(0)-alkyne interaction has yet to be established. Here, a Pd(0)-π-Lewis base activation mode is proposed and investigated by combining theoretical and experimental studies. In this activation mode, the Pd(0) coordinates to the alkyne group and enhances its nucleophilicity through π-back-donation, facilitating the nucleophilic attack on the aldehyde to generate a trans-Pd(ii)-vinyl complex. Ligand-effect studies reveal that the more electron-donating one would accelerate the reaction, and the cyclization of the challenging flexible C- or O-tethered substrates has been realized. The origin of regioselectivities is also explicated by the newly proposed metal π-Lewis base activation mode.
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Affiliation(s)
- Lei Zhu
- College of Pharmacy, Third Military Medical University Shapingba Chongqing 400038 China
- Breast and Thyroid Surgery, Southwest Hospital, Third Military Medical University Shapingba Chongqing 400038 China
| | - Bo Zhao
- College of Pharmacy, Third Military Medical University Shapingba Chongqing 400038 China
| | - Ke Xie
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Ministry of Education and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University Chengdu 610041 China
| | - Wu-Tao Gui
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Ministry of Education and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University Chengdu 610041 China
| | - Sheng-Li Niu
- College of Pharmacy, Third Military Medical University Shapingba Chongqing 400038 China
| | - Peng-Fei Zheng
- College of Pharmacy, Third Military Medical University Shapingba Chongqing 400038 China
| | - Ying-Chun Chen
- College of Pharmacy, Third Military Medical University Shapingba Chongqing 400038 China
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Ministry of Education and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University Chengdu 610041 China
| | - Xiao-Wei Qi
- Breast and Thyroid Surgery, Southwest Hospital, Third Military Medical University Shapingba Chongqing 400038 China
| | - Qin Ouyang
- College of Pharmacy, Third Military Medical University Shapingba Chongqing 400038 China
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2
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Aksenov AV, Makieva DC, Arestov RA, Arutiunov NA, Aksenov DA, Aksenov NA, Leontiev AV, Aksenova IV. Metal-Free, PPA-Mediated Fisher Indole Synthesis via Tandem Hydroamination-Cyclization Reaction between Simple Alkynes and Arylhydrazines. Int J Mol Sci 2024; 25:8750. [PMID: 39201437 DOI: 10.3390/ijms25168750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2024] [Revised: 08/08/2024] [Accepted: 08/09/2024] [Indexed: 09/02/2024] Open
Abstract
A new variant of Fisher indole synthesis involving Bronsted acid-catalyzed hydrohydrazination of unactivated terminal and internal acetylenes with arylhydrazines is reported. The use of polyphosphoric acid alone either as the reaction medium or in the presence of a co-solvent appears to provide the required balance for activating the C-C triple bond towards the nucleophilic attack of the hydrazine moiety without unrepairable reactivity loss of the latter due to competing amino group protonation. Additionally, the formal hydration of acetylenes to the corresponding ketones occurs under the same conditions, making it an alternative approach for generating carbonyl groups from alkynes.
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Affiliation(s)
- Alexander V Aksenov
- Department of Chemistry, North Caucasus Federal University, 1a Pushkin St., 355017 Stavropol, Russia
| | - Dinara C Makieva
- Department of Chemistry, North Caucasus Federal University, 1a Pushkin St., 355017 Stavropol, Russia
| | - Rodion A Arestov
- Department of Chemistry, North Caucasus Federal University, 1a Pushkin St., 355017 Stavropol, Russia
| | - Nikolai A Arutiunov
- Department of Chemistry, North Caucasus Federal University, 1a Pushkin St., 355017 Stavropol, Russia
| | - Dmitrii A Aksenov
- Department of Chemistry, North Caucasus Federal University, 1a Pushkin St., 355017 Stavropol, Russia
| | - Nicolai A Aksenov
- Department of Chemistry, North Caucasus Federal University, 1a Pushkin St., 355017 Stavropol, Russia
| | - Alexander V Leontiev
- Department of Chemistry, North Caucasus Federal University, 1a Pushkin St., 355017 Stavropol, Russia
| | - Inna V Aksenova
- Department of Chemistry, North Caucasus Federal University, 1a Pushkin St., 355017 Stavropol, Russia
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3
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Lu QT, Du YB, Xu MM, Xie PP, Cai Q. Catalytic Asymmetric Aza-Electrophilic Additions of 1,1-Disubstituted Styrenes. J Am Chem Soc 2024; 146:21535-21545. [PMID: 39056748 DOI: 10.1021/jacs.4c04852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2024]
Abstract
Electrophilic addition of alkenes is a textbook reaction that plays a pivotal role in organic chemistry. In the past decades, catalytic asymmetric variants of this important type of reaction have witnessed great achievements by the development of novel catalytic systems. However, enantioselective aza-electrophilic additions of unactivated alkenes, which could provide a transformative strategy for the preparation of synthetically significant nitrogen-containing compounds, still remain a formidable challenge. Herein, we have developed unprecedented Au(I)/NHC-catalyzed asymmetric aza-electrophilic additions of unactivated 1,1-disubstituted styrenes by the utilization of readily available dialkyl azodicarboxylates as electrophilic nitrogen sources. Based on this approach, a series of transformations, including [2 + 2] cycloaddition, intermolecular 1,2-oxyamination, and several types of intramolecular hydrazination-induced cyclizations, have been realized. These transformations provide a previously unattainable platform for the divergent synthesis of hydrazine derivatives, which could also be converted to other nitrogen-containing chiral synthons. Experimental and computational studies support the idea that carbocation intermediates are involved in reaction pathways.
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Affiliation(s)
- Qi-Tao Lu
- Department of Chemistry, Research Center for Molecular Recognition and Synthesis, Fudan University, Shanghai 200433, China
| | - Yuan-Bo Du
- Department of Chemistry, Research Center for Molecular Recognition and Synthesis, Fudan University, Shanghai 200433, China
| | - Meng-Meng Xu
- Department of Chemistry, Research Center for Molecular Recognition and Synthesis, Fudan University, Shanghai 200433, China
| | - Pei-Pei Xie
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Quan Cai
- Department of Chemistry, Research Center for Molecular Recognition and Synthesis, Fudan University, Shanghai 200433, China
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4
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Lin A, Lee S, Knowles RR. Organic Synthesis Away from Equilibrium: Contrathermodynamic Transformations Enabled by Excited-State Electron Transfer. Acc Chem Res 2024; 57:1827-1838. [PMID: 38905487 DOI: 10.1021/acs.accounts.4c00227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/23/2024]
Abstract
ConspectusChemists have long been inspired by biological photosynthesis, wherein a series of excited-state electron transfer (ET) events facilitate the conversion of low energy starting materials such as H2O and CO2 into higher energy products in the form of carbohydrates and O2. While this model for utilizing light-driven charge transfer to drive catalytic reactions thermodynamically "uphill" has been extensively adapted for small molecule activation, molecular machines, photoswitches, and solar fuel chemistry, its application in organic synthesis has been less systematically developed. However, the potential benefits of these approaches are significant, both in enabling transformations that cannot be readily achieved using conventional thermal chemistry and in accessing distinct selectivity regimes that are uniquely enabled by excited-state mechanisms. In this Account, we present work from our group that highlights the ability of visible light photoredox catalysis to drive useful organic transformations away from their equilibrium positions, addressing a number of long-standing synthetic challenges.We first discuss how excited-state ET enabled the first general methods for the catalytic anti-Markovnikov hydroamination of unactivated alkenes with alkyl amines. In these reactions, an excited-state iridium(III) photocatalyst reversibly oxidizes secondary amine substrates to their corresponding aminium radical cations (ARCs). These electrophilic N-centered radicals can then react with olefins to furnish valuable tertiary amine products with complete anti-Markovnikov regioselectivity. Notably, some of these products are less thermodynamically stable than their corresponding amine and alkene starting materials. We next present a strategy for light-driven C-C bond cleavage within various aliphatic alcohols mediated by homolytic activation of alcohol O-H bonds by excited-state proton-coupled electron transfer (PCET). The resulting alkoxy radical intermediates then undergo C-C β-scission to ultimately provide isomeric linear carbonyl products that are often higher in energy than their cyclic alcohol precursors. Applications of this chemistry for the light-driven depolymerization of lignin biomass, commercial phenoxy resin, hydroxylated polyolefin derivatives, and thermoset polymers are presented as well. We then describe a method for the contrathermodynamic positional isomerization of highly substituted olefins by means of cooperative photoredox and chromium(II) catalysis. In this work, generation of an allylchromium(III) species that can undergo highly regioselective in situ protodemetalation enables access to a less substituted and thermodynamically less stable positional isomer. Product selectivity in this reaction is determined by the large differential in oxidation potentials between differently substituted olefin isomers. Lastly, we discuss a light-driven deracemization reaction developed in collaboration with the Miller group, wherein a racemic urea substrate undergoes spontaneous optical enrichment upon visible light irradiation in the presence of an iridium(III) chromophore, a chiral Brønsted base, and a chiral peptide thiol. Excellent levels of enantioselectivity are achieved via sequential and synergistic proton transfer (PT) and H atom transfer (HAT) steps. Taken together, these examples highlight the ability of excited-state ET events to enable access to nonequilibrium product distributions across a wide range of catalytic, redox-neutral transformations in which photons are the only stoichiometric reagents.
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Affiliation(s)
- Angela Lin
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Sumin Lee
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Robert R Knowles
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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5
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Zhang J, Huan XD, Wang X, Li GQ, Xiao WJ, Chen JR. Recent advances in C(sp 3)-N bond formation via metallaphoto-redox catalysis. Chem Commun (Camb) 2024; 60:6340-6361. [PMID: 38832416 DOI: 10.1039/d4cc01969e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
The C(sp3)-N bond is ubiquitous in natural products, pharmaceuticals, biologically active molecules and functional materials. Consequently, the development of practical and efficient methods for C(sp3)-N bond formation has attracted more and more attention. Compared to the conventional ionic pathway-based thermal methods, photochemical processes that proceed through radical mechanisms by merging photoredox and transition-metal catalyses have emerged as powerful and alternative tools for C(sp3)-N bond formation. In this review, recent advances in the burgeoning field of C(sp3)-N bond formation via metallaphotoredox catalysis have been highlighted. The contents of this review are categorized according to the transition metals used (copper, nickel, cobalt, palladium, and iron) together with photocatalysis. Emphasis is placed on methodology achievements and mechanistic insight, aiming to inspire chemists to invent more efficient radical-involved C(sp3)-N bond-forming reactions.
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Affiliation(s)
- Juan Zhang
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
| | - Xiao-Die Huan
- College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan, Hubei 430079, China.
| | - Xin Wang
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
| | - Guo-Qing Li
- College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan, Hubei 430079, China.
| | - Wen-Jing Xiao
- College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan, Hubei 430079, China.
| | - Jia-Rong Chen
- College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan, Hubei 430079, China.
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6
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Liu Y, Huang J, Sun Z, Deng Y, Qian Y, Huang Q, Cao S. Two-step synthesis of vicinal trifluoromethyl primary amines from α-(trifluoromethyl)styrenes and phthalimide. Org Biomol Chem 2024; 22:4641-4646. [PMID: 38775720 DOI: 10.1039/d4ob00567h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
A novel two-step synthesis of β-trifluoromethyl primary amines from readily available α-(trifluoromethyl)styrenes and phthalimide is developed. The first step involves a hydroamination between α-(trifluoromethyl)styrenes and phthalimide (PhthNH) with the assistance of a base. Next, the hydrazinolysis of the resulting N-(β-trifluoromethyl-β-arylethyl)phthalimides with hydrazine hydrate affords the desired N-(β-trifluoromethyl-β-arylethyl)amines.
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Affiliation(s)
- Ying Liu
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology (ECUST), Shanghai 200237, China.
| | - Jiaqi Huang
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology (ECUST), Shanghai 200237, China.
| | - Zhudi Sun
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology (ECUST), Shanghai 200237, China.
| | - Yupian Deng
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology (ECUST), Shanghai 200237, China.
| | - Yuhao Qian
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology (ECUST), Shanghai 200237, China.
| | - Qingchun Huang
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology (ECUST), Shanghai 200237, China.
| | - Song Cao
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology (ECUST), Shanghai 200237, China.
- Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, China
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7
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Pradhan TR, Farah AO, Sagar K, Wise HR, Srimannarayana M, Cheong PHY, Park JK. Acetate Assistance in Regioselective Hydroamination of Allenamides: A Combined Experimental and Density Functional Theory Study. J Org Chem 2024; 89:5927-5940. [PMID: 38651750 DOI: 10.1021/acs.joc.3c02509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
A key factor in the development of selective nucleophilic addition to allenamides is controlling the reactivity of electrophilic intermediates, which is generally achieved using an electrophilic activator via conjugated iminium intermediates. In this combined experimental and computational study, we show that a general and highly chemoselective hydroamination of allenamides can be accomplished using a combination of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and NaOAc. Experimental mechanistic studies revealed that HFIP mediates proton transfer to activate the allenamide, while the acetate additive significantly contributes to N-selective interception. This strategy enables a general hydroamination of allenamides without the use of metals. We demonstrated that various functionalized 1,3-diamines could be readily synthesized and diversified into value-added structural motifs. Detailed mechanistic investigations using the density functional theory revealed the role of NaOAc in the formation of reactive electrophilic intermediates, which ultimately governed the selective formation of 1,3-diamine products. Critically, calculations of the potential energy surface around the proton-transfer transition state revealed that two different reactive electrophilic intermediates were formed when NaOAc was added.
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Affiliation(s)
- Tapas R Pradhan
- Department of Chemistry and Chemistry Institution for Functional Materials, Pusan National University, Busan 46241, Republic of Korea
| | - Abdikani Omar Farah
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Kadiyala Sagar
- Department of Chemistry, School of Science, GITAM University (Hyderabad Campus), Telangana 502329, India
- Medicinal Chemistry Division, Aragen Life Sciences Pvt. Ltd., Hyderabad 500076, India
| | - Henry R Wise
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Malempati Srimannarayana
- Department of Chemistry, School of Science, GITAM University (Hyderabad Campus), Telangana 502329, India
| | - Paul Ha-Yeon Cheong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Jin Kyoon Park
- Department of Chemistry and Chemistry Institution for Functional Materials, Pusan National University, Busan 46241, Republic of Korea
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8
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Panahi F, Breit B. Rhodium-Catalyzed Asymmetric Macrocyclization towards Crown Ethers Using Hydroamination of Bis(allenes). Angew Chem Int Ed Engl 2024; 63:e202317981. [PMID: 38323896 DOI: 10.1002/anie.202317981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 02/06/2024] [Accepted: 02/06/2024] [Indexed: 02/08/2024]
Abstract
Enantiomerically enriched crown ethers (CE) exhibit strong asymmetric induction in phase transfer catalysis, supramolecular catalysis and molecular recognition processes. Traditional methods have often been used to access these valuable compounds, which limit their diversity and consequently their applicability. Herein, a practical catalytic method is described for the gram scale synthesis of a class of chiral CEs (aza-crown ethers; ACEs) using Rh-catalyzed hydroamination of bis(allenes) with diamines. Using this approach, a wide range of chiral vinyl functionalized CEs with ring sizes ranging from 12 to 36 have been successfully prepared in high yields of up to 92 %, dr of up to >20 : 1 and er of up to >99 : 1. These vinyl substituted CEs allow for further diversification giving facile access to various CE derivatives as well as to their three-dimensional analogues using ring-closing metathesis. Some of these chiral CEs themselves display high potential for use in asymmetric catalysis.
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Affiliation(s)
- Farhad Panahi
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg im Breisgau, Germany
| | - Bernhard Breit
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg im Breisgau, Germany
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9
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Wang CJ, Meng HJ, Tang Y, Chen J, Zhou L. Aromatic Amine and Chiral Phosphoric Acid Synergistic Catalyzed Cascade Reaction of Alkynylnaphthols with Aldehydes. Org Lett 2024; 26:1489-1494. [PMID: 38358098 DOI: 10.1021/acs.orglett.4c00172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2024]
Abstract
A novel approach using aromatic amines and chiral phosphoric acids in a synergistic catalytic cascade reaction of 2-alkynylnaphthols with aldehydes has been established. This method offers a direct route to preparing flavanone analogues with excellent stereoselectivity. Mechanistic studies reveal a sequential process involving addition, elimination, cyclization, and hydrolysis in which aromatic amines and chiral phosphoric acids play key roles via imine-enamine and hydrogen bonding models.
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Affiliation(s)
- Chuan-Jin Wang
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, Department of Chemistry & Materials Science, Northwest University, Xi'an 710127, P. R. China
| | - Hao-Jie Meng
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, Department of Chemistry & Materials Science, Northwest University, Xi'an 710127, P. R. China
| | - Yue Tang
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, Department of Chemistry & Materials Science, Northwest University, Xi'an 710127, P. R. China
| | - Jie Chen
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, Department of Chemistry & Materials Science, Northwest University, Xi'an 710127, P. R. China
| | - Ling Zhou
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, Department of Chemistry & Materials Science, Northwest University, Xi'an 710127, P. R. China
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10
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Faculak MS, Veatch AM, Alexanian EJ. Cobalt-catalyzed synthesis of amides from alkenes and amines promoted by light. Science 2024; 383:77-81. [PMID: 38175889 PMCID: PMC10799253 DOI: 10.1126/science.adk2312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 11/20/2023] [Indexed: 01/06/2024]
Abstract
Catalytic methods to couple alkene and amine feedstocks are valuable in synthetic chemistry. The direct carbonylative coupling of alkenes and amines holds promise as a perfectly atom-economical approach to amide synthesis, but general methods remain underdeveloped. Herein, we report an alkene hydroaminocarbonylation catalyzed by unmodified, inexpensive cobalt carbonyl under mild conditions and low pressure promoted by light. Silane addition after the reaction enables sequential cobalt-catalyzed amide reduction, constituting a formal alkene hydroaminomethylation. These methods exhibit exceptional scope across both alkene and amine components with high chemo- and regioselectivity and proceed efficiently even in the absence of solvent. The formation of a hydridocobalt through photodissociation of a carbonyl ligand is proposed to enable catalytic activity under mild conditions, which addresses a long-standing challenge in catalysis.
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Affiliation(s)
- Mason S Faculak
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Alexander M Veatch
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Erik J Alexanian
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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11
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Wang L, Shi M, Chen X, Su N, Luo W, Zhang X. Generation of Aromatic N-Heterocyclic Radicals for Functionalization of Unactivated Alkenes. Angew Chem Int Ed Engl 2023; 62:e202314312. [PMID: 37946626 DOI: 10.1002/anie.202314312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Revised: 10/30/2023] [Accepted: 11/09/2023] [Indexed: 11/12/2023]
Abstract
Nitrogen-centered radicals (NCRs) have been widely recognized as versatile synthetic intermediates for the construction of nitrogen containing molecules of high value. As such, there has been a long-standing interest in the field of organic synthesis to develop novel nitrogen-based radicals and explore their inherent reactivity. In this study, we present the generation of aromatic N-heterocyclic radicals and their application in a novel and diverse functionalization of unactivated alkenes. Bench-stable aromatic N-heterocyclic pyridinium salts were employed as crucial NCR precursors, which enabled the efficient conversion of various unactivated alkenes into medicinally relevant alkylated N-heterocyclic amines. This approach offers an unexplored retrosynthetic disconnection for the synthesis of related molecules that commonly possess therapeutic value. Furthermore, this platform can be extended to the synthesis of densely functionalized heterocyclic amines by utilizing disulfides and diethyl bromomalonate as radical quenchers. Mechanistic investigations indicate an energy transfer (EnT) pathway involving the formation of a transient aromatic N-heterocyclic radical, radical addition to unactivated alkenes, and subsequent generation of the amination product through either hydrogen atom transfer (HAT) or radical addition processes.
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Affiliation(s)
- Lu Wang
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Minxu Shi
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Xiaoping Chen
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Nicholas Su
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Weili Luo
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Xiaheng Zhang
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
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12
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Geunes EP, Meinhardt JM, Wu EJ, Knowles RR. Photocatalytic Anti-Markovnikov Hydroamination of Alkenes with Primary Heteroaryl Amines. J Am Chem Soc 2023; 145:21738-21744. [PMID: 37787499 PMCID: PMC10589911 DOI: 10.1021/jacs.3c08428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
We report a light-driven method for the intermolecular anti-Markovnikov hydroamination of alkenes with primary heteroaryl amines. In this protocol, electron transfer between an amine substrate and an excited-state iridium photocatalyst affords an aminium radical cation (ARC) intermediate that undergoes C-N bond formation with a nucleophilic alkene. Integral to reaction success is the electronic character of the amine, wherein increasingly electron-deficient heteroaryl amines generate increasingly reactive ARCs. Counteranion-dependent reactivity is observed, and iridium triflate photocatalysts are employed in place of conventional iridium hexafluorophosphate complexes. This method exhibits broad functional group tolerance across 55 examples of N-alkylated products derived from pharmaceutically relevant heteroaryl amines.
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Affiliation(s)
- Eric P Geunes
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Jonathan M Meinhardt
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Emily J Wu
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Robert R Knowles
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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13
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Li F, Luo Y, Ren J, Yuan Q, Yan D, Zhang W. Iridium-Catalyzed Remote Site-Switchable Hydroarylation of Alkenes Controlled by Ligands. Angew Chem Int Ed Engl 2023; 62:e202309859. [PMID: 37610735 DOI: 10.1002/anie.202309859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/23/2023] [Accepted: 08/23/2023] [Indexed: 08/24/2023]
Abstract
An iridium-catalyzed remote site-switchable hydroarylation of alkenes was reported, delivering the products functionalized at the subterminal methylene and terminal methyl positions on an alkyl chain controlled by two different ligands, respectively, in good yields and with good to excellent site-selectivities. The catalytic system showed good functional group tolerance and a broad substrate scope, including unactivated and activated alkenes. More importantly, the regioconvergent transformations of mixtures of isomeric alkenes were also successfully realized. The results of the mechanistic studies demonstrate that the reaction undergoes a chain-walking process to give an [Ar-Ir-H] complex of terminal alkene. The subsequent processes proceed through the modified Chalk-Harrod-type mechanism via the migratory insertion of terminal alkene into the Ir-C bond followed by C-H reductive elimination to afford the hydrofunctionalization products site-selectively.
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Affiliation(s)
- Fei Li
- Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Yicong Luo
- Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Jinbao Ren
- Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Qianjia Yuan
- Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Deyue Yan
- Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Wanbin Zhang
- Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
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