1
|
Phelps J, Kumar R, Robinson JD, Chu JCK, Flodén NJ, Beaton S, Gaunt MJ. Multicomponent Synthesis of α-Branched Amines via a Zinc-Mediated Carbonyl Alkylative Amination Reaction. J Am Chem Soc 2024; 146:9045-9062. [PMID: 38488310 PMCID: PMC10996026 DOI: 10.1021/jacs.3c14037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 02/09/2024] [Accepted: 02/20/2024] [Indexed: 03/21/2024]
Abstract
Methods for the synthesis of α-branched alkylamines are important due to their ubiquity in biologically active molecules. Despite the development of many methods for amine preparation, C(sp3)-rich nitrogen-containing compounds continue to pose challenges for synthesis. While carbonyl reductive amination (CRA) between ketones and alkylamines is the cornerstone method for α-branched alkylamine synthesis, it is sometimes limited by the sterically demanding condensation step between dialkyl ketones and amines and the more restricted availability of ketones compared to aldehydes. We recently reported a "higher-order" variant of this transformation, carbonyl alkylative amination (CAA), which utilized a halogen atom transfer (XAT)-mediated radical mechanism, enabling the streamlined synthesis of complex α-branched alkylamines. Despite the efficacy of this visible-light-driven approach, it displayed scalability issues, and competitive reductive amination was a problem for certain substrate classes, limiting applicability. Here, we report a change in the reaction regime that expands the CAA platform through the realization of an extremely broad zinc-mediated CAA reaction. This new strategy enabled elimination of competitive CRA, simplified purification, and improved reaction scope. Furthermore, this new reaction harnessed carboxylic acid derivatives as alkyl donors and facilitated the synthesis of α-trialkyl tertiary amines, which cannot be accessed via CRA. This Zn-mediated CAA reaction can be carried out at a variety of scales, from a 10 μmol setup in microtiter plates enabling high-throughput experimentation, to the gram-scale synthesis of medicinally-relevant compounds. We believe that this transformation enables robust, efficient, and economical access to α-branched alkylamines and provides a viable alternative to the current benchmark methods.
Collapse
Affiliation(s)
| | | | | | | | - Nils J. Flodén
- Yusuf Hamied Department of
Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Sarah Beaton
- Yusuf Hamied Department of
Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Matthew J. Gaunt
- Yusuf Hamied Department of
Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| |
Collapse
|
2
|
He C, Wang Q, Zhou X, Yi L, Zhang Z, Zhang C, Xie H, Huang Q, Qiu G, Yang M. Photocatalytic Cyclization Cascades by Radical Relay toward Pyrrolo[1,2- a]indoles: Synthesis, Mechanism, and Application. J Org Chem 2024; 89:3509-3524. [PMID: 38362658 DOI: 10.1021/acs.joc.3c02959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
A photocatalytic annulation cascade of unactivated N-alkene-linked indoles with Langlois' reagent by a radical relay is developed at room temperature under blue LED irradiation. The reaction afforded a series of tri/difluoromethylated pyrrolo[1,2-a]indoles in moderate to good yields. The DFT study suggests that the reaction is ascribed to a rhodamine 6G-induced cyclization cascade involving vinyl addition-radical relay and hydrogen-atom-abstraction (HAA) processes, and interestingly, pyrrolo[1,2-a]indoles are applied as fluorescent dyes into the fluorescence spectrum and live-cell imaging. This paper represents an initial example on photocatalytic cyclization cascades by radical relay and the HAA process.
Collapse
Affiliation(s)
- Chen He
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| | - Qi Wang
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| | - Xiaoyang Zhou
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| | - Lin Yi
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| | - Zhiqiang Zhang
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| | - Chun Zhang
- School of Pharmaceutical and Materials Engineering, Taizhou University, Taizhou, Zhejiang Province 318000, China
| | - Haijiao Xie
- Hangzhou Yanqu Information Technology Co., Ltd., Y2, second Floor, Building 2, Xixi Legu Creative Pioneering Park, No. 712 Wen'er West Road, Xihu District, Hangzhou City, Zhejiang Province 310003, China
| | - Qitong Huang
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| | - Guanyinsheng Qiu
- College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001 Zhejiang, China
| | - Min Yang
- School of Pharmacy, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Biomedical Sensors of Ganzhou, Gannan Medical University, Ganzhou, Jiangxi Province 341000, China
| |
Collapse
|
3
|
Zhang T, Jiang S, Qian MY, Zhou QL, Xiao LJ. Ligand-Controlled Regiodivergent Nickel-Catalyzed Hydroaminoalkylation of Unactivated Alkenes. J Am Chem Soc 2024; 146:3458-3470. [PMID: 38270100 DOI: 10.1021/jacs.3c13060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2024]
Abstract
Ligand modulation of transition-metal catalysts to achieve optimal reactivity and selectivity in alkene hydrofunctionalization is a fundamental challenge in synthetic organic chemistry. Hydroaminoalkylation, an atom-economical approach for alkylating amines using alkenes, is particularly significant for amine synthesis in the pharmaceutical, agrochemical, and fine chemical industries. However, the existing methods usually require specific substrate combinations to achieve precise regio- and stereoselectivity, which limits their practical utility. Protocols allowing for regiodivergent hydroaminoalkylation from the same starting materials, controlling both regiochemical and stereochemical outcomes, are currently absent. Herein, we report a ligand-controlled, regiodivergent nickel-catalyzed hydroaminoalkylation of unactivated alkenes with N-sulfonyl amines. The reaction initiates with amine dehydrogenation and involves aza-nickelacycle intermediates. Tritert-butylphosphine promotes branched regioselectivity and syn diastereoselectivity, whereas ethyldiphenylphosphine enables linear selectivity, yielding regioisomers with inverse orientation. Systematic evaluation of diverse monodentate phosphine ligands reveals distinct regioselectivity cliffs, and % Vbur (min), a ligand steric descriptor, was established as a predictive parameter correlating ligand structure to regioselectivity. Computational investigations supported experimental findings, offering mechanistic insights into the origins of regioselectivity. Our method provides an efficient and predictable route for amine synthesis, demonstrating broad substrate scope, excellent tolerance toward various functional groups, and practical advantages. These include the use of readily available starting materials and cost-effective nickel(II) salts as precatalysts.
Collapse
Affiliation(s)
- Tianze Zhang
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Frontiers Science Center for New Organic Matter, Nankai University, Tianjin 300071, China
| | - Shan Jiang
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Frontiers Science Center for New Organic Matter, Nankai University, Tianjin 300071, China
| | - Meng-Ying Qian
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Frontiers Science Center for New Organic Matter, Nankai University, Tianjin 300071, China
| | - Qi-Lin Zhou
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Frontiers Science Center for New Organic Matter, Nankai University, Tianjin 300071, China
| | - Li-Jun Xiao
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Frontiers Science Center for New Organic Matter, Nankai University, Tianjin 300071, China
| |
Collapse
|
4
|
Li J, Gong S, Gao S, Chen J, Chen WW, Zhao B. Asymmetric α-C(sp 3)-H allylic alkylation of primary alkylamines by synergistic Ir/ketone catalysis. Nat Commun 2024; 15:939. [PMID: 38296941 PMCID: PMC10830461 DOI: 10.1038/s41467-024-45131-3] [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: 10/05/2023] [Accepted: 01/12/2024] [Indexed: 02/02/2024] Open
Abstract
Primary alkyl amines are highly reactive in N-nucleophilic reactions with electrophiles. However, their α-C-H bonds are unreactive towards electrophiles due to their extremely low acidity (pKa ~57). Nonetheless, 1,8-diazafluoren-9-one (DFO) can activate primary alkyl amines by increasing the acidity of the α-amino C-H bonds by up to 1044 times. This makes the α-amino C-H bonds acidic enough to be deprotonated under mild conditions. By combining DFO with an iridium catalyst, direct asymmetric α-C-H alkylation of NH2-unprotected primary alkyl amines with allylic carbonates has been achieved. This reaction produces a wide range of chiral homoallylic amines with high enantiopurities. The approach has successfully switched the reactivity between primary alkyl amines and allylic carbonates from intrinsic allylic amination to the α-C-H alkylation, enabling the construction of pharmaceutically significant chiral homoallylic amines from readily available primary alkyl amines in a single step.
Collapse
Affiliation(s)
- Jianyu Li
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Frontiers Science Center of Biomimetic Catalysis and Shanghai Normal University, Shanghai, 200234, China
| | - Sheng Gong
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Frontiers Science Center of Biomimetic Catalysis and Shanghai Normal University, Shanghai, 200234, China
| | - Shaolun Gao
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Frontiers Science Center of Biomimetic Catalysis and Shanghai Normal University, Shanghai, 200234, China
| | - Jianfeng Chen
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Frontiers Science Center of Biomimetic Catalysis and Shanghai Normal University, Shanghai, 200234, China.
| | - Wen-Wen Chen
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Frontiers Science Center of Biomimetic Catalysis and Shanghai Normal University, Shanghai, 200234, China
| | - Baoguo Zhao
- The Education Ministry Key Lab of Resource Chemistry, Shanghai Frontiers Science Center of Biomimetic Catalysis and Shanghai Normal University, Shanghai, 200234, China.
| |
Collapse
|
5
|
Meng X, Dong Y, Liu Q, Wang W. Organophotocatalytic α-deuteration of unprotected primary amines via H/D exchange with D 2O. Chem Commun (Camb) 2024; 60:296-299. [PMID: 38054348 PMCID: PMC10872390 DOI: 10.1039/d3cc04634f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
We report a straightforward H/D exchange method for the synthesis of α-deuterated primary amines from a diverse set of primary amines with high levels of deuteration and chemo- and site selectivity and preparative utility. This cost-effective strategy enables the direct conversion of primary amines to α-deuterated counterparts using D2O as the deuterium source under mild reaction conditions without requiring additional functionality manipulation and with minimal byproduct production.
Collapse
Affiliation(s)
- Xiang Meng
- Department of Pharmacology and Toxicology, R. Ken Coit College of Pharmacy, University of Arizona, USA.
| | - Yue Dong
- Department of Pharmacology and Toxicology, R. Ken Coit College of Pharmacy, University of Arizona, USA.
| | - Qiangqiang Liu
- Department of Pharmacology and Toxicology, R. Ken Coit College of Pharmacy, University of Arizona, USA.
| | - Wei Wang
- Department of Pharmacology and Toxicology, R. Ken Coit College of Pharmacy, University of Arizona, USA.
- Department of Chemistry and Biochemistry, University of Arizona, USA
- University of Arizona Cancer Centre, University of Arizona, 1703 E. Mabel Street, Tucson, AZ 85721-0207, USA
| |
Collapse
|
6
|
Ghosh SK, He L, Tang Z, Comito RJ. Selective and Functional-Group-Tolerant Photoalkylation of Imines by Energy-Transfer Photocatalysis. J Org Chem 2023; 88:15209-15217. [PMID: 37875007 DOI: 10.1021/acs.joc.3c01722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
Basic amines show broad bioactivity and remain a promising source of new medicines. The direct photoalkylation of imines offers a promising strategy for complex amines. However, the lack of efficient imine photoreactivity hinders this reaction and remains a fundamental limitation in organic photochemistry. We report an efficient photoalkylation of imines that provides primary amines directly without protecting or leaving groups. The transformation effects C-H addition across N-H imines under energy-transfer photocatalysis by a ketone. Our method is distinguished from organometallic, metal-catalyzed, and photoredox approaches to imine alkylation by its lack of protecting groups and its broad scope, which includes unactivated alkanes, protic substrates, basic amines, heterocycles, and ketone imines. We highlight this scope through the condensation and alkylation of two pharmaceutical ketones, providing complex amines succinctly. Our mechanistic analysis supports a three-step process, involving hydrogen-atom transfer to an imine triplet excited state, intersystem crossing, and radical recombination, with photocatalytic enhancement through energy transfer. We further show that N-H imines are more photoreactive than N-substituted imines, a distinction partially explained by sterics and side reactions. To fully explain this distinction, we introduce the thermodynamic parameter excited-state hydrogen-atom affinity, which is highly effective at predicting the photoreactivity of imines.
Collapse
Affiliation(s)
- Subrata K Ghosh
- The University of Houston, 4800 Calhoun Road, Houston, Texas 77004, United States
| | - Lizhe He
- The University of Houston, 4800 Calhoun Road, Houston, Texas 77004, United States
| | - Zilu Tang
- The University of Houston, 4800 Calhoun Road, Houston, Texas 77004, United States
| | - Robert J Comito
- The University of Houston, 4800 Calhoun Road, Houston, Texas 77004, United States
| |
Collapse
|
7
|
Schneider JE, Anderson JS. Reconciling Imbalanced and Nonadiabatic Reactivity in Transition Metal-Oxo-Mediated Concerted Proton Electron Transfer (CPET). J Phys Chem Lett 2023; 14:9548-9555. [PMID: 37856336 DOI: 10.1021/acs.jpclett.3c02318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
Recently, there have been several experimental demonstrations of how the rates of concerted proton electron transfer (CPET) are affected by stepwise thermodynamic parameters of only proton (ΔG°PT) or electron (ΔG°ET) transfer. Semiclassical structure-activity relationships have been invoked to rationalize these linear free energy relationships, but it is not clear how they would manifest in a nonadiabatic reaction. Using density functional theory calculations, we demonstrate how a decrease in ΔG°PT can lead to transition state imbalance in a nonadiabatic framework. We then use these calculations to anchor a theoretical model that reproduces experimental trends with ΔG°PT and ΔG°ET. Our results reconcile predictions from semiclassical transition state theory with models that treat proton transfer quantum mechanically in CPET reactivity, make new predictions about the importance of basicity for uphill CPET reactions, and suggest similar treatments may be possible for other nonadiabatic reactions.
Collapse
Affiliation(s)
- Joseph E Schneider
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - John S Anderson
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| |
Collapse
|
8
|
Cao Q, Tibbetts JD, Wrigley GL, Smalley AP, Cresswell AJ. Modular, automated synthesis of spirocyclic tetrahydronaphthyridines from primary alkylamines. Commun Chem 2023; 6:215. [PMID: 37794068 PMCID: PMC10550966 DOI: 10.1038/s42004-023-01012-2] [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: 07/13/2023] [Accepted: 09/22/2023] [Indexed: 10/06/2023] Open
Abstract
Spirocyclic tetrahydronaphthyridines (THNs) are valuable scaffolds for drug discovery campaigns, but access to this 3D chemical space is hampered by a lack of modular and scalable synthetic methods. We hereby report an automated, continuous flow synthesis of α-alkylated and spirocyclic 1,2,3,4-tetrahydro-1,8-naphthyridines ("1,8-THNs"), in addition to their regioisomeric 1,6-THN analogues, from abundant primary amine feedstocks. An annulative disconnection approach based on photoredox-catalysed hydroaminoalkylation (HAA) of halogenated vinylpyridines is sequenced in combination with intramolecular SNAr N-arylation. To access the remaining 1,7- and 1,5-THN isomers, a photoredox-catalysed HAA step is telescoped with a palladium-catalysed C-N bond formation. Altogether, this provides a highly modular access to four isomeric THN cores from a common set of unprotected primary amine starting materials, using the same bond disconnections. The simplifying power of the methodology is illustrated by a concise synthesis of the spirocyclic THN core of Pfizer's MC4R antagonist PF-07258669.
Collapse
Affiliation(s)
- Qiao Cao
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Joshua D Tibbetts
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Gail L Wrigley
- Medicinal Chemistry, Oncology R&D, AstraZeneca, Cambridge, CB4 0WG, UK
| | | | | |
Collapse
|
9
|
Meger FS, Murphy JA. Recent Advances in C-H Functionalisation through Indirect Hydrogen Atom Transfer. Molecules 2023; 28:6127. [PMID: 37630379 PMCID: PMC10459052 DOI: 10.3390/molecules28166127] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/09/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
The functionalisation of C-H bonds has been an enormous achievement in synthetic methodology, enabling new retrosynthetic disconnections and affording simple synthetic equivalents for synthons. Hydrogen atom transfer (HAT) is a key method for forming alkyl radicals from C-H substrates. Classic reactions, including the Barton nitrite ester reaction and Hofmann-Löffler-Freytag reaction, among others, provided early examples of HAT. However, recent developments in photoredox catalysis and electrochemistry have made HAT a powerful synthetic tool capable of introducing a wide range of functional groups into C-H bonds. Moreover, greater mechanistic insights into HAT have stimulated the development of increasingly site-selective protocols. Site-selectivity can be achieved through the tuning of electron density at certain C-H bonds using additives, a judicious choice of HAT reagent, and a solvent system. Herein, we describe the latest methods for functionalizing C-H/Si-H/Ge-H bonds using indirect HAT between 2018-2023, as well as a critical discussion of new HAT reagents, mechanistic aspects, substrate scopes, and background contexts of the protocols.
Collapse
Affiliation(s)
- Filip S. Meger
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, 16 Avinguda dels Països Catalans, 43007 Tarragona, Catalonia, Spain
| | - John A. Murphy
- Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, UK
| |
Collapse
|
10
|
Sneha M, Thornton GL, Lewis-Borrell L, Ryder ASH, Espley SG, Clark IP, Cresswell AJ, Grayson MN, Orr-Ewing AJ. Photoredox-HAT Catalysis for Primary Amine α-C-H Alkylation: Mechanistic Insight with Transient Absorption Spectroscopy. ACS Catal 2023; 13:8004-8013. [PMID: 37342833 PMCID: PMC10278065 DOI: 10.1021/acscatal.3c01474] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/17/2023] [Indexed: 06/23/2023]
Abstract
The synergistic use of (organo)photoredox catalysts with hydrogen-atom transfer (HAT) cocatalysts has emerged as a powerful strategy for innate C(sp3)-H bond functionalization, particularly for C-H bonds α- to nitrogen. Azide ion (N3-) was recently identified as an effective HAT catalyst for the challenging α-C-H alkylation of unprotected, primary alkylamines, in combination with dicyanoarene photocatalysts such as 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN). Here, time-resolved transient absorption spectroscopy over sub-picosecond to microsecond timescales provides kinetic and mechanistic details of the photoredox catalytic cycle in acetonitrile solution. Direct observation of the electron transfer from N3- to photoexcited 4CzIPN reveals the participation of the S1 excited electronic state of the organic photocatalyst as an electron acceptor, but the N3• radical product of this reaction is not observed. Instead, both time-resolved infrared and UV-visible spectroscopic measurements implicate rapid association of N3• with N3- (a favorable process in acetonitrile) to form the N6•- radical anion. Electronic structure calculations indicate that N3• is the active participant in the HAT reaction, suggesting a role for N6•- as a reservoir that regulates the concentration of N3•.
Collapse
Affiliation(s)
- Mahima Sneha
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
- Department
of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, United States
| | - Georgia L. Thornton
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - Luke Lewis-Borrell
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - Alison S. H. Ryder
- Centre
for Sustainable Chemical Technologies, University
of Bath, 1 South, Claverton Down, Bath BA2 7AY, U.K.
| | - Samuel G. Espley
- Department
of Chemistry, University of Bath, 1 South, Claverton Down, Bath BA2 7AY, U.K.
| | - Ian P. Clark
- Central
Laser Facility, Research Complex at Harwell, Science and Technology
Facilities Council, Rutherford Appleton
Laboratory, Harwell Oxford, Didcot OX11 0QX, U.K.
| | - Alexander J. Cresswell
- Department
of Chemistry, University of Bath, 1 South, Claverton Down, Bath BA2 7AY, U.K.
| | - Matthew N. Grayson
- Department
of Chemistry, University of Bath, 1 South, Claverton Down, Bath BA2 7AY, U.K.
| | - Andrew J. Orr-Ewing
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| |
Collapse
|
11
|
Hao H, Manßen M, Schafer LL. Tantalum ureate complexes for photocatalytic hydroaminoalkylation. Chem Sci 2023; 14:4928-4934. [PMID: 37181785 PMCID: PMC10171191 DOI: 10.1039/d3sc00042g] [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: 01/03/2023] [Accepted: 03/13/2023] [Indexed: 05/16/2023] Open
Abstract
Using a tantalum ureate pre-catalyst, photocatalytic hydroaminoalkylation of unactivated alkenes with unprotected amines at room temperature is demonstrated. The combination of Ta(CH2SiMe3)3Cl2 and a ureate ligand with a saturated cyclic backbone resulted in this unique reactivity. Preliminary investigations of the reaction mechanism suggest that both the thermal and photocatalytic hydroaminoalkylation reactions begin with N-H bond activation and subsequent metallaaziridine formation. However, a select tantalum ureate complex, through ligand to metal charge transfer (LMCT), results in photocatalyzed homolytic metal-carbon bond cleavage and subsequent addition to unactivated alkene to afford the desired carbon-carbon bond formation. Origins of ligand effects on promoting homolytic metal-carbon bond cleavage are explored computationally to support enhanced ligand design efforts.
Collapse
Affiliation(s)
- Han Hao
- Department of Chemistry, University of Toronto Toronto Ontario M5S 3H6 Canada
| | - Manfred Manßen
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen Auf der Morgenstelle 18 72076 Tübingen Germany
| | - Laurel L Schafer
- Department of Chemistry, University of British Columbia Vancouver British Columbia V6T 1Z4 Canada
| |
Collapse
|
12
|
Xu Y, Wang J, Deng GJ, Shao W. Recent advances in the synthesis of chiral α-tertiary amines via transition-metal catalysis. Chem Commun (Camb) 2023; 59:4099-4114. [PMID: 36919669 DOI: 10.1039/d3cc00439b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
The significance of chiral α-tertiary amines in medicinal chemistry and drug development has been unquestionably established in the last few decades. α-Tertiary amines are attractive structural motifs for natural products, bioactive molecules and pharmaceuticals and are preclinical candidates. Their syntheses have been the focus of intensive research, and the development of new methods has continued to attract more and more attention. In this review, we present the progress in the last decade in the development of synthetic methods for the assembly of chiral ATAs via transition-metal catalysis. To date, the effective approaches in this area could be categorized into three strategies: enantioselective direct and indirect Mannich addition to ketimines; umpolung asymmetric alkylation of imine derivatives; and asymmetric C-N cross-coupling of tertiary alkyl electrophiles. Several related developing strategies for the synthesis of ATAs, such as hydroamination of alkenes, HAT amination approaches and the C-C coupling of α-aminoalkyl fragments, are also described in this article. These strategies have emerged as attractive C-C and C-N bond-forming protocols for enantioselective construction of chiral α-tertiary amines, and to some extent are complementary to each other, showing the prospect of application in medicinal chemistry and chemical biology.
Collapse
Affiliation(s)
- Yongzhuo Xu
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, P. R. China.
| | - Jiajia Wang
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, P. R. China.
| | - Guo-Jun Deng
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, P. R. China.
| | - Wen Shao
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, P. R. China.
| |
Collapse
|
13
|
Nilova A, Mannchen MD, Noel AN, Semenova E, Grenning AJ. Vicinal stereocenters via asymmetric allylic alkylation and Cope rearrangement: a straightforward route to functionally and stereochemically rich heterocycles. Chem Sci 2023; 14:2755-2762. [PMID: 36908968 PMCID: PMC9993902 DOI: 10.1039/d2sc07021a] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 02/13/2023] [Indexed: 02/16/2023] Open
Abstract
An asymmetric allylic alkylation/Cope rearrangement (AAA/[3,3]) capable of stereoselectively constructing vicinal stereocenters has been developed. Strategically integrated 4-methylation on the 3,3-dicyano-1,5-diene controls stereoselectivity and drives Cope rearrangement equilibrium in the forward direction. The AAA/[3,3] sequence rapidly converts abundant achiral and racemic starting materials into valuable (hetero)cycloalkane building blocks bearing significant functional and stereochemical complexity, highlighting the value of (hetero)cyclohexylidenemalononitriles as launching points for complex heterocycle synthesis. On this line, the resulting alkylidenemalononitrile moiety can be readily converted into amides via Hayashi-Lear amidation to ultimately yield amido-piperidines, tropanes, and related scaffolds with 3-5 stereocenters and drug-like functionality.
Collapse
Affiliation(s)
- Aleksandra Nilova
- Department of Chemistry, University of Florida PO Box 117200 Gainesville 32611 FL USA
| | - Michael D Mannchen
- Department of Chemistry, University of Florida PO Box 117200 Gainesville 32611 FL USA
| | - Abdias N Noel
- Department of Chemistry, University of Florida PO Box 117200 Gainesville 32611 FL USA
| | - Evgeniya Semenova
- Department of Chemistry, University of Florida PO Box 117200 Gainesville 32611 FL USA
| | - Alexander J Grenning
- Department of Chemistry, University of Florida PO Box 117200 Gainesville 32611 FL USA
| |
Collapse
|
14
|
Dubois MAJ, Rojas JJ, Sterling AJ, Broderick HC, Smith MA, White AJP, Miller PW, Choi C, Mousseau JJ, Duarte F, Bull JA. Visible Light Photoredox-Catalyzed Decarboxylative Alkylation of 3-Aryl-Oxetanes and Azetidines via Benzylic Tertiary Radicals and Implications of Benzylic Radical Stability. J Org Chem 2023; 88:6476-6488. [PMID: 36868184 DOI: 10.1021/acs.joc.3c00083] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
Four-membered heterocycles offer exciting potential as small polar motifs in medicinal chemistry but require further methods for incorporation. Photoredox catalysis is a powerful method for the mild generation of alkyl radicals for C-C bond formation. The effect of ring strain on radical reactivity is not well understood, with no studies that address this question systematically. Examples of reactions that involve benzylic radicals are rare, and their reactivity is challenging to harness. This work develops a radical functionalization of benzylic oxetanes and azetidines using visible light photoredox catalysis to prepare 3-aryl-3-alkyl substituted derivatives and assesses the influence of ring strain and heterosubstitution on the reactivity of small-ring radicals. 3-Aryl-3-carboxylic acid oxetanes and azetidines are suitable precursors to tertiary benzylic oxetane/azetidine radicals which undergo conjugate addition into activated alkenes. We compare the reactivity of oxetane radicals to other benzylic systems. Computational studies indicate that Giese additions of unstrained benzylic radicals into acrylates are reversible and result in low yields and radical dimerization. Benzylic radicals as part of a strained ring, however, are less stable and more π-delocalized, decreasing dimer and increasing Giese product formation. Oxetanes show high product yields due to ring strain and Bent's rule rendering the Giese addition irreversible.
Collapse
Affiliation(s)
- Maryne A J Dubois
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, U.K
| | - Juan J Rojas
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, U.K
| | - Alistair J Sterling
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3TA, U.K
| | - Hannah C Broderick
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, U.K
| | - Milo A Smith
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, U.K
| | - Andrew J P White
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, U.K
| | - Philip W Miller
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, U.K
| | - Chulho Choi
- Pfizer Global Research and Development, 445 Eastern Point Rd., Groton, Connecticut 06340, United States
| | - James J Mousseau
- Pfizer Global Research and Development, 445 Eastern Point Rd., Groton, Connecticut 06340, United States
| | - Fernanda Duarte
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3TA, U.K
| | - James A Bull
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, U.K
| |
Collapse
|
15
|
Wiley RE, McLaughlin MF, Johnson JS. Dearomatization of Cyclic Diphenylhydrazines: Harnessing the o-Semidine Rearrangement for the Synthesis of Spirocyclic Tetrahydroquinolines. Org Lett 2022; 24:8014-8018. [PMID: 36269213 PMCID: PMC9678246 DOI: 10.1021/acs.orglett.2c03220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The synthesis of novel tetrahydroquinoline-containing spirocycles has been achieved through an acid-promoted dearomatization of cyclic diarylhydrazines. The reaction, proceeding through a dearomative o-semidine rearrangement, furnishes a stable, yet reactive spirocyclohexadieniminium ion, which can further be used as an electrophile or a diene in a one-pot sequence. These transformations efficiently produce novel diazaspirocycles and allow for further synthetic elaboration of the cyclohexadienamine products.
Collapse
Affiliation(s)
- Robert E Wiley
- University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 25799-3290, United States
| | - Michael F McLaughlin
- University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 25799-3290, United States
| | - Jeffrey S Johnson
- University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 25799-3290, United States
| |
Collapse
|
16
|
Cascade cyclization of alkene-tethered acylsilanes and allylic sulfones enabled by unproductive energy transfer photocatalysis. Nat Commun 2022; 13:6111. [PMID: 36245017 PMCID: PMC9573877 DOI: 10.1038/s41467-022-33730-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 09/29/2022] [Indexed: 11/09/2022] Open
Abstract
Developing photo-induced cascade cyclization of alkene-tethered acylsilanes is challenging, because acylsilanes are unstable under light irradiation. Herein, we report that the energy transfer from excited acylsilanes to a photocatalyst that possesses lower triplet energy can inhibit the undesired decomposition of acylsilanes. With neutral Eosin Y as the photocatalyst, an efficient synthesis of cyclopentanol derivatives is achieved with alkene-tethered acylsilanes and allylic sulfones. The reaction shows broad substrate scope and the synthetic potential of this transformation is highlighted by the construction of cyclopentanol derivatives which contain fused-ring or bridged-ring. Acylsilanes decompose under light irradiation, and this limits their use in light-induced organic transformations. Here the authors report a strategy to inhibit the light-induced decomposition of acylsilanes, enabling the photochemical synthesis of cyclopentanol derivatives from alkene-tethered acylsilanes and allylic sulfones.
Collapse
|
17
|
Merkens K, Sanosa N, Funes-Ardoiz I, Gómez-Suárez A. Accessing α-Amino Ketyl Radicals from β-Amino Alcohols via Chemoselective Hydrogen Atom Transfer Catalysis. ACS Catal 2022. [DOI: 10.1021/acscatal.2c03724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kay Merkens
- Organic Chemistry, Bergische Universität Wuppertal, Gaußstr. 20, 42119 Wuppertal, Germany
| | - Nil Sanosa
- Department of Chemistry, Centro de Investigación en Síntesis Química (CISQ), Universidad de La Rioja, Madre de Dios 53, 26004 Logroño, Spain
| | - Ignacio Funes-Ardoiz
- Department of Chemistry, Centro de Investigación en Síntesis Química (CISQ), Universidad de La Rioja, Madre de Dios 53, 26004 Logroño, Spain
| | - Adrián Gómez-Suárez
- Organic Chemistry, Bergische Universität Wuppertal, Gaußstr. 20, 42119 Wuppertal, Germany
| |
Collapse
|
18
|
Zheng S, Wang W, Yuan W. Remote and Proximal Hydroaminoalkylation of Alkenes Enabled by Photoredox/Nickel Dual Catalysis. J Am Chem Soc 2022; 144:17776-17782. [PMID: 36136777 DOI: 10.1021/jacs.2c08039] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A mild and site-selective hydroaminoalkylation of activated and unactivated alkenes via dual photoredox/Ni catalysis is developed. This dual catalytic strategy enables exclusive access to α-selective products, which is complementary to previously reported photocatalytic hydroaminoalkylation of activated alkenes that provides the β-selective products. The chain-walking of a Ni-H intermediate toward a carbonyl allows for the hydroaminoalkylation of unactivated alkenes at remote sp3 C-H sites. This method tolerates a broad substrate scope of both amines and alkenes as well as providing a streamlined synthesis of value-added β-amino acid derivatives from readily available starting materials.
Collapse
Affiliation(s)
- Songlin Zheng
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Hubei Key Laboratory of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Road, Wuhan 430074, China
| | - Wenlong Wang
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Hubei Key Laboratory of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Road, Wuhan 430074, China
| | - Weiming Yuan
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Hubei Key Laboratory of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu Road, Wuhan 430074, China.,Shenzhen Huazhong University of Science and Technology Research Institute, Shenzhen 518000, China.,Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen 518055, China
| |
Collapse
|
19
|
Swords WB, Chapman SJ, Hofstetter H, Dunn AL, Yoon TP. Variable Temperature LED-NMR: Rapid Insights into a Photocatalytic Mechanism from Reaction Progress Kinetic Analysis. J Org Chem 2022; 87:11776-11782. [PMID: 35969669 DOI: 10.1021/acs.joc.2c01479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A multitude of techniques are available to obtain a useful understanding of photocatalytic mechanisms. The combination of LED illumination with nuclear magnetic resonance spectroscopy (LED-NMR) provides a rapid, convenient means to directly monitor a photocatalytic reaction in situ. Herein, we describe a study of the mechanism of an enantioselective intermolecular [2 + 2] photocycloaddition catalyzed by a chiral Ir photocatalyst using LED-NMR. The data-rich output of this experiment is suitable for same-excess and variable time normalization analyses (VTNA). Together, these identified an unexpected change in mechanism between reactions conducted at ambient and cryogenic temperatures. At -78 °C, the kinetic data are consistent with the triplet rebound mechanism we previously proposed for this reaction, involving sensitization of maleimide and rapid reaction with a hydrogen-bound quinoline within the solvent cage. At room temperature, the cycloaddition instead proceeds through intracomplex energy transfer to the hydrogen-bound quinolone. These results highlight the potential sensitivity of photocatalytic reaction mechanisms to the precise reaction conditions and the further utility of LED-NMR as a fast, data-rich tool for their interrogation that compares favorably to conventional ex situ kinetic analyses.
Collapse
Affiliation(s)
- Wesley B Swords
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53703, United States
| | - Steven J Chapman
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53703, United States
| | - Heike Hofstetter
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53703, United States
| | - Anna L Dunn
- Drug Product Development, GlaxoSmithKline, Upper Providence, Pennsylvania19426, United States
| | - Tehshik P Yoon
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53703, United States
| |
Collapse
|
20
|
Harenberg JH, Reddy Annapureddy R, Karaghiosoff K, Knochel P. Continuous Flow Preparation of Benzylic Sodium Organometallics. Angew Chem Int Ed Engl 2022; 61:e202203807. [PMID: 35416397 PMCID: PMC9400861 DOI: 10.1002/anie.202203807] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Indexed: 12/14/2022]
Abstract
We report a lateral sodiation of alkyl(hetero)arenes using on‐demand generated hexane‐soluble (2‐ethylhexyl)sodium (1) in the presence of TMEDA. (2‐Ethylhexyl)sodium (1) is prepared via a sodium packed‐bed reactor and used for metalations at ambient temperature in batch as well as in continuous flow. The resulting benzylic sodium species are subsequently trapped with various electrophiles including carbonyl compounds, epoxides, oxetane, allyl/benzyl chlorides, alkyl halides and alkyl tosylates. Wurtz‐type couplings with secondary alkyl halides and tosylates proceed under complete inversion of stereochemistry. Furthermore, the utility of this lateral sodiation is demonstrated in the synthesis of pharmaceutical relevant compounds. Thus, fingolimod is prepared from p‐xylene applying the lateral sodiation twice. In addition, 7‐fold isotopically labeled salmeterol‐d7 and fenpiprane as well as precursors to super linear alkylbenzene (SLAB) surfactants are prepared.
Collapse
Affiliation(s)
- Johannes H. Harenberg
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstraße 5–13, Haus F81377MünchenGermany
| | | | - Konstantin Karaghiosoff
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstraße 5–13, Haus F81377MünchenGermany
| | - Paul Knochel
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstraße 5–13, Haus F81377MünchenGermany
| |
Collapse
|
21
|
DiPucchio RC, Rosca SC, Schafer LL. Hydroaminoalkylation for the Catalytic Addition of Amines to Alkenes or Alkynes: Diverse Mechanisms Enable Diverse Substrate Scope. J Am Chem Soc 2022; 144:11459-11481. [PMID: 35731810 DOI: 10.1021/jacs.1c10397] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Hydroaminoalkylation is a powerful, atom-economic catalytic reaction for the reaction of amines with alkenes and alkynes. This C-H functionalization reaction allows for the atom-economic alkylation of amines using simple alkenes or alkynes as the alkylating agents. This transformation has significant potential for transformative approaches in the pharmaceutical, agrochemical, and fine chemical industries in the preparation of selectively substituted amines and N-heterocycles and shows promise in materials science for the synthesis of functional and responsive aminated materials. Different early transition-metal, late transition-metal, and photoredox catalysts mediate hydroaminoalkylation by distinct mechanistic pathways. These mechanistic insights have resulted in the development of new catalysts and reaction conditions to realize hydroaminoalkylation with a broad range of substrates: activated and unactivated, terminal and internal, C-C double and triple bonds with aryl or alkyl primary, secondary, or tertiary amines, including N-heterocyclic amines. By deploying select catalysts with specific substrate combinations, control over regioselectivity, diastereoselectivity, and enantioselectivity has been realized. Key barriers to widespread adoption of this reaction include air and moisture sensitivity for early transition-metal catalysts as well as a heavy dependence on amine protecting or directing groups for late transition-metal or photocatalytic routes. Advances in improved catalyst robustness, substrate scope, and regio-/stereoselective reactions with early- and late transition-metal catalysts, as well as photoredox catalysis, are highlighted, and opportunities for further catalyst and reaction development are included. This perspective shows that hydroaminoalkylation has the potential to be a disruptive and transformative strategy for the synthesis of selectively substituted amines and N-heterocycles from simple amines and alkenes.
Collapse
Affiliation(s)
- Rebecca C DiPucchio
- Department of Chemistry, The University of British Columbia, Vancouver, BC, Canada, V6T 1Z1
| | - Sorin-Claudiu Rosca
- Department of Chemistry, The University of British Columbia, Vancouver, BC, Canada, V6T 1Z1
| | - Laurel L Schafer
- Department of Chemistry, The University of British Columbia, Vancouver, BC, Canada, V6T 1Z1
| |
Collapse
|
22
|
Shee M, Singh NDP. Photogenerated Azido Radical Mediated Oxidation: Access to Carbonyl Functionality from Alcohols, Alkylarenes, and Olefins via Organophotoredox. Adv Synth Catal 2022. [DOI: 10.1002/adsc.202200242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Maniklal Shee
- Department of Chemistry Indian Institute of Technology Kharagpur 721302 Kharagpur West Bengal India
| | - N. D. Pradeep Singh
- Department of Chemistry Indian Institute of Technology Kharagpur 721302 Kharagpur West Bengal India
| |
Collapse
|
23
|
Zheng J, Tang N, Xie H, Breit B. Regio-, Diastereo-, and Enantioselective Decarboxylative Hydroaminoalkylation of Dienol Ethers Enabled by Dual Palladium/Photoredox Catalysis. Angew Chem Int Ed Engl 2022; 61:e202200105. [PMID: 35170841 PMCID: PMC9314026 DOI: 10.1002/anie.202200105] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Indexed: 12/15/2022]
Abstract
Intermolecular photocatalytic hydroaminoalkylation (HAA) of alkenes have emerged as a powerful method for the construction of alkyl amines. Although there are some studies aiming at stereoselective photocatalytic HAA reactions, the alkenes are limited to electrophilic alkenes. Herein, we report a highly regio‐, diastereo‐, and enantioselective HAA of electron‐rich dienol ethers and α‐amino radicals derived from α‐amino acids using a unified photoredox and palladium catalytic system. This decarboxylative 1,2‐Markovnikov addition enables the construction of vicinal amino tertiary ethers with high levels of regio‐ (up to >19 : 1 rr), diastereo‐ (up to >19 : 1 dr), and enantioselectivity control (up to >99 % ee). Mechanistic studies support a reversible hydropalladation as a key step.
Collapse
Affiliation(s)
- Jun Zheng
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg im Breisgau, Germany
| | - Nana Tang
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg im Breisgau, Germany
| | - Hui Xie
- 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
| |
Collapse
|
24
|
Sakai K, Oisaki K, Kanai M. A Germanium Catalyst Accelerates the Photoredox α-C(sp 3)-H Alkylation of Primary Amines. Org Lett 2022; 24:3325-3330. [PMID: 35486160 DOI: 10.1021/acs.orglett.2c00871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Site-selective C(sp3)-H functionalizations using photoredox catalysis (PC) and hydrogen atom transfer (HAT) catalysis have received increasing attention. Here, we report a Ph2GeCl2 cocatalyst that greatly improves the yield of α-C(sp3)-H alkylation of primary amines catalyzed by a PC-HAT hybrid system. The α-position of the amino group selectively reacted even when weaker C-H bonds existed in the substrates. This finding may help the design of a novel site-selective hybrid catalysis.
Collapse
Affiliation(s)
- Kentaro Sakai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Kounosuke Oisaki
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Motomu Kanai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| |
Collapse
|
25
|
Harenberg JH, Annapureddy RR, Karaghiosoff K, Knochel P. Continuous Flow Preparation of Benzylic Sodium Organometallics. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202203807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | | | | | - Paul Knochel
- Ludwig-Maximilians-Universitat Munchen Department of Chemistry Butenandtstr. 5-13 81377 München GERMANY
| |
Collapse
|
26
|
Maity A, Roychowdhury P, Herrera RG, Powers DC. Diversification of Amidyl Radical Intermediates Derived from C-H Aminopyridylation. Org Lett 2022; 24:2762-2766. [PMID: 35377670 PMCID: PMC9089237 DOI: 10.1021/acs.orglett.2c00869] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The N-activating substituents typically encountered in C-H amination chemistry are challenging to remove and have limited scope for synthetic elaboration. Here, we demonstrate that N-benzylaminopyridinium species provide a platform for synthetic elaboration via reductive N-N bond activation to unveil electrophilic N-centered radicals. These reactive intermediates can be trapped either via anti-Markovnikov olefin carboamination to provide access to tetrahydroisoquinolines or via aza-Rubottom chemistry with silyl enol ethers to provide α-amino ketones.
Collapse
Affiliation(s)
- Asim Maity
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Pritam Roychowdhury
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Roberto G Herrera
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - David C Powers
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| |
Collapse
|
27
|
Zheng J, Tang N, Xie H, Breit B. Regio‐, Diastereo‐, and Enantioselective Decarboxylative Hydro‐aminoalkylation of Dienol Ethers Enabled by Dual Palladium/Pho‐toredox Catalysis. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202200105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Jun Zheng
- Institut für Organische Chemie Albert-Ludwigs-Universität Freiburg Albertstraße 21 79104 Freiburg im Breisgau Germany
| | - Nana Tang
- Institut für Organische Chemie Albert-Ludwigs-Universität Freiburg Albertstraße 21 79104 Freiburg im Breisgau Germany
| | - Hui Xie
- 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
| |
Collapse
|
28
|
Shee M, Singh NDP. Chemical versatility of azide radical: journey from a transient species to synthetic accessibility in organic transformations. Chem Soc Rev 2022; 51:2255-2312. [PMID: 35229836 DOI: 10.1039/d1cs00494h] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The generation of azide radical (N3˙) occurs from its precursors primarily via a single electron transfer (SET) process or homolytic cleavage by chemical methods or advanced photoredox/electrochemical methods. This in situ generated transient open-shell species has unique characteristic features that set its reactivity. In the past, the azide radical was widely used for various studies in radiation chemistry as a 1e- oxidant of biologically important molecules, but now it is being exploited for synthetic applications based on its addition and intermolecular hydrogen atom transfer (HAT) abilities. Due to the significant role of nitrogen-containing molecules in synthesis, drug discovery, biological, and material sciences, the direct addition onto unsaturated bonds for the simultaneous construction of C-N bond with other (C-X) bonds are indeed worth highlighting. Moreover, the ability to generate O- or C-centered radicals by N3˙ via electron transfer (ET) and intermolecular HAT processes is also well documented. The purpose of controlling the reactivity of this short-lived intermediate in organic transformations drives us to survey: (i) the history of azide radical and its structural properties (thermodynamic, spectroscopic, etc.), (ii) chemical reactivities and kinetics, (iii) methods to produce N3˙ from various precursors, (iv) several significant azide radical-mediated transformations in the field of functionalization with unsaturated bonds, C-H functionalization via HAT, tandem, and multicomponent reaction with a critical analysis of underlying mechanistic approaches and outcomes, (v) concept of taming the reactivity of azide radicals for potential opportunities, in this review.
Collapse
Affiliation(s)
- Maniklal Shee
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India.
| | - N D Pradeep Singh
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India.
| |
Collapse
|
29
|
Grayson JD, Askey HE, Turner-Dore JC, Cresswell AJ. Styrene hydroaminoalkylation with primary alkylamines. TRENDS IN CHEMISTRY 2022. [DOI: 10.1016/j.trechm.2022.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
30
|
Gentleman AS, Lawson T, Ellis MG, Davis M, Turner-Dore J, Ryder ASH, Frosz MH, Ciaccia M, Reisner E, Cresswell AJ, Euser TG. Stern–Volmer analysis of photocatalyst fluorescence quenching within hollow-core photonic crystal fibre microreactors. Chem Commun (Camb) 2022; 58:10548-10551. [DOI: 10.1039/d2cc03996f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Optofluidic microreactors enable Stern–Volmer analysis on nanolitre-scale photocatalyst–quencher mixtures. The method is used to measure bimolecular quenching coefficients for a photoredox-catalysed α-C–H alkylation reaction of primary alkylamines.
Collapse
Affiliation(s)
- Alexander S. Gentleman
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Takashi Lawson
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Matthew G. Ellis
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Molly Davis
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Jacob Turner-Dore
- Department of Chemistry, University of Bath, 1 South, Claverton Down, Bath, BA2 7AY, UK
| | - Alison S. H. Ryder
- Department of Chemistry, University of Bath, 1 South, Claverton Down, Bath, BA2 7AY, UK
| | - Michael H. Frosz
- Max Planck Institute for the Science of Light, Staudtstr. 2, 91058, Erlangen, Germany
| | - Maria Ciaccia
- Syngenta, Jealott's Hill Research Centre, Bracknell, Berkshire, RG52 6EY, UK
| | - Erwin Reisner
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | | | - Tijmen G. Euser
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| |
Collapse
|
31
|
Mandigma MJP, Žurauskas J, MacGregor CI, Edwards LJ, Shahin A, d'Heureuse L, Yip P, Birch DJS, Gruber T, Heilmann J, John MP, Barham JP. An organophotocatalytic late-stage N–CH3 oxidation of trialkylamines to N-formamides with O2 in continuous flow. Chem Sci 2022; 13:1912-1924. [PMID: 35308839 PMCID: PMC8849051 DOI: 10.1039/d1sc05840a] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 12/26/2021] [Indexed: 12/25/2022] Open
Abstract
We report an organophotocatalytic, N–CH3-selective oxidation of trialkylamines in continuous flow. Based on the 9,10-dicyanoanthracene (DCA) core, a new catalyst (DCAS) was designed with solubilizing groups for flow processing. This allowed O2 to be harnessed as a sustainable oxidant for late-stage photocatalytic N–CH3 oxidations of complex natural products and active pharmaceutical ingredients bearing functional groups not tolerated by previous methods. The organophotocatalytic gas–liquid flow process affords cleaner reactions than in batch mode, in short residence times of 13.5 min and productivities of up to 0.65 g per day. Spectroscopic and computational mechanistic studies showed that catalyst derivatization not only enhanced solubility of the new catalyst compared to poorly-soluble DCA, but profoundly diverted the photocatalytic mechanism from singlet electron transfer (SET) reductive quenching with amines toward energy transfer (EnT) with O2. An N–CH3-selective trialkylamine oxidation to N-formamides is reported in continuous flow using gaseous O2. A novel, enhanced-solubility dicyanoanthracene organophotocatalyst switched the photochemical mechanism from electron to energy transfer.![]()
Collapse
Affiliation(s)
- Mark John P. Mandigma
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Jonas Žurauskas
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Callum I. MacGregor
- GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK
| | - Lee J. Edwards
- GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK
| | - Ahmed Shahin
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
- Chemistry Department, Faculty of Science, Benha University, 13518 Benha, Egypt
| | - Ludwig d'Heureuse
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Philip Yip
- Department of Physics, SUPA, University of Strathclyde, 107 Rottenrow East, Glasgow, G4 0NG, UK
| | - David J. S. Birch
- Department of Physics, SUPA, University of Strathclyde, 107 Rottenrow East, Glasgow, G4 0NG, UK
| | - Thomas Gruber
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Jörg Heilmann
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| | - Matthew P. John
- GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK
| | - Joshua P. Barham
- Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
| |
Collapse
|