1
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Kim J, Rodriguez KX, Eckert KE, Oliver AG, Ashfeld BL. A Rh II-Catalyzed [4 + 3]-Cycloaddition via the Stereoselective Cyclopropanation of Vinyl Allenes En Route to Oxepino[ b]indoles and Subsequent Elaboration to Spirooxindole Frameworks. Org Lett 2025; 27:5003-5008. [PMID: 40311032 DOI: 10.1021/acs.orglett.5c01329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2025]
Abstract
Oxepino[b]indoles were obtained in good to excellent yields employing a [4 + 3]-cycloaddition initiated by a stereo- and regioselective, RhII-catalyzed cyclopropanation between a vinyl allene and diazooxindole to afford an intermediate cyclopropyl allene that engaged the oxindole carbonyl in a spontaneous hetero-[3,3]-rearrangement. A survey of functional group tolerance revealed a diverse array of substrates amenable to oxepino[b]indole formation. In addition to the intriguing architecture of the cycloadducts, exposure to either Brønsted acid or base enables the assembly of functionalized spirroxindoles via the unusual conversion of a 5-7 fused ring system to a 5-5 spirocycle.
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Affiliation(s)
- Jiyoon Kim
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Kevin X Rodriguez
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Kaitlyn E Eckert
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Allen G Oliver
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Brandon L Ashfeld
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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2
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Zhang J, Xu X, Yang K, Li M, Liu Y, Song H, Wang Q. Silver-catalyzed cascade cyclization for the synthesis of 4-aminotetrahydrocarbazole. Chem Commun (Camb) 2024; 60:12573-12576. [PMID: 39387149 DOI: 10.1039/d4cc03723e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2024]
Abstract
A silver-catalyzed cascade cyclization strategy has been developed for the synthesis of 4-aminotetrahydrocarbazole, a common core structure found in various alkaloids. This target molecule can be synthesized through a one-step tandem cyclization reaction, thereby eliminating the need for a prior synthesis of tetrahydrocarbazole. Furthermore, the use of chiral tert-butylsulfinamide facilitates in situ chiral resolution of the resulting product.
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Affiliation(s)
- Jingjing Zhang
- Key Laboratory of Smart Breeding (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs, Tianjin Agricultural University, Tianjin 300384, China
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, People's Republic of China.
| | - Xinxin Xu
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, People's Republic of China.
| | - Kangkang Yang
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, People's Republic of China.
| | - Mingxing Li
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, People's Republic of China.
| | - Yuxiu Liu
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, People's Republic of China.
| | - Hongjian Song
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, People's Republic of China.
| | - Qingmin Wang
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, People's Republic of China.
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3
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Wonilowicz LG, Mehta MM, Kamecke L, French SA, Garg NK. Diels-Alder Cycloadditions of Oxacyclic Allenes and α-Pyrones. Org Lett 2024; 26:6465-6470. [PMID: 39046907 PMCID: PMC11459240 DOI: 10.1021/acs.orglett.4c02294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
Reactions of α-pyrones with oxacyclic allenes in Diels-Alder trappings are described. We investigate regioselectivity trends and perform competition experiments to assess the influence of structural and electronic features on relative reaction rates. We also demonstrate the stereospecific trapping of an oxacyclic allene, which proceeds in high optical yield. This study provides insight into strained cyclic allene reactivity, as well as new synthetic tools for the rapid construction of complex, heterocyclic scaffolds.
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Affiliation(s)
| | | | - Lisa Kamecke
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
| | - Sarah A. French
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
| | - Neil K. Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
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4
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McVeigh MS, Sorrentino JP, Hands AT, Garg NK. Access to Complex Scaffolds Through [2 + 2] Cycloadditions of Strained Cyclic Allenes. J Am Chem Soc 2024; 146:15420-15427. [PMID: 38768558 PMCID: PMC11459239 DOI: 10.1021/jacs.4c03369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
We report the strain-induced [2 + 2] cycloadditions of cyclic allenes for the assembly of highly substituted cyclobutanes. By judicious choice of trapping agent, complex scaffolds bearing heteroatoms, fused rings, contiguous stereocenters, spirocycles, and quaternary centers are ultimately accessible. Moreover, we show that the resulting cycloadducts can undergo thermal isomerization. This study provides an alternative strategy to photochemical [2 + 2] cycloadditions for accessing highly functionalized cyclobutanes, while validating the use of underexplored strained intermediates for the assembly of complex architectures.
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Affiliation(s)
- Matthew S McVeigh
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Jacob P Sorrentino
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Allison T Hands
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Neil K Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
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5
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Vampugani NMR, Shelke AB, Singh PB, Ahmad A, Kapat A. Regioselective Synthesis of the Tetrahydrocarbazole Core of Akuammiline Alkaloids via Palladium-Catalyzed Intramolecular Arylation Reaction. J Org Chem 2024; 89:4461-4466. [PMID: 38527008 DOI: 10.1021/acs.joc.3c02619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
Tetrahydrocarbazole is the central core for several biologically active alkaloids, and regioselective synthesis of this core is a challenging task. Herein, we report an efficient strategy for the synthesis of this core involving palladium-catalyzed intramolecular arylation reaction with excellent regioselectivity (>99%) starting from N-phenyl-bromoalkene without having any relocation of double bonds via competitive palladium-catalyzed isomerization reaction. Broad functional group tolerance and exclusive regioselectivity have been observed for meta-substituted halide substrates. Furthermore, this reaction can be scalable on the gram scale.
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Affiliation(s)
- Naga M R Vampugani
- Department of Chemistry, School of Natural Sciences, Shiv Nadar (Institution of Eminence Deemed to be University) Delhi-NCR, Dadri, Chithera, Gautam Buddha Nagar, Greater Noida, Uttar Pradesh 201314, India
| | - Ajay B Shelke
- Department of Chemistry, School of Natural Sciences, Shiv Nadar (Institution of Eminence Deemed to be University) Delhi-NCR, Dadri, Chithera, Gautam Buddha Nagar, Greater Noida, Uttar Pradesh 201314, India
| | - Prashant B Singh
- Department of Chemistry, School of Natural Sciences, Shiv Nadar (Institution of Eminence Deemed to be University) Delhi-NCR, Dadri, Chithera, Gautam Buddha Nagar, Greater Noida, Uttar Pradesh 201314, India
| | - Asrar Ahmad
- Department of Chemistry, School of Natural Sciences, Shiv Nadar (Institution of Eminence Deemed to be University) Delhi-NCR, Dadri, Chithera, Gautam Buddha Nagar, Greater Noida, Uttar Pradesh 201314, India
| | - Ajoy Kapat
- Department of Chemistry, School of Natural Sciences, Shiv Nadar (Institution of Eminence Deemed to be University) Delhi-NCR, Dadri, Chithera, Gautam Buddha Nagar, Greater Noida, Uttar Pradesh 201314, India
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6
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Wang B, Ren M, Iqbal N, Mu X, Bäckvall JE, Yang B. Palladium-Catalyzed Dehydrogenative Carbonylative Esterification of Allenoic Acids for the Synthesis of γ-Butyrolactone Derivatives. Org Lett 2024. [PMID: 38502799 DOI: 10.1021/acs.orglett.4c00572] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
A highly efficient dehydrogenative carbonylative esterification of allenoic acids using Pd-catalysis was developed, providing a novel approach to synthesizing esterified γ-butyrolactone derivatives with consistently good to excellent results demonstrated across over 50 examples. Additionally, we used a heterogeneous catalyst known as Pd-AmP-MCF and harnessed biomimetic-aerobic-oxidation conditions to facilitate the practical execution of this reaction. Furthermore, our detailed study of γ-butyrolactone products highlighted their potential in synthesizing bioactive compounds.
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Affiliation(s)
- Bolin Wang
- School of Chemistry, Xi'an Jiaotong University, 710049, Xi'an, P. R. China
| | - Mingzhe Ren
- School of Chemistry, Xi'an Jiaotong University, 710049, Xi'an, P. R. China
| | - Nasir Iqbal
- School of Chemistry, Xi'an Jiaotong University, 710049, Xi'an, P. R. China
| | - Xin Mu
- School of Chemistry, Xi'an Jiaotong University, 710049, Xi'an, P. R. China
| | - Jan-E Bäckvall
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
| | - Bin Yang
- School of Chemistry, Xi'an Jiaotong University, 710049, Xi'an, P. R. China
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7
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Kelleghan AV, Meza AT, Garg NK. Generation and reactivity of unsymmetrical strained heterocyclic allenes. NATURE SYNTHESIS 2024; 3:329-336. [PMID: 38645473 PMCID: PMC11031199 DOI: 10.1038/s44160-023-00432-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 10/04/2023] [Indexed: 04/23/2024]
Abstract
Strained cyclic allenes are short-lived intermediates that confine a functional group with a preferred linear geometry, an allene, into a small ring, inducing strain-driven reactivity. Nitrogen-containing variants, or azacyclic allenes, have proved valuable for the assembly of complex nitrogen-containing compounds. Whereas 3,4-azacyclic allenes, which bear a symmetrical core, have been the focus of multiple studies, their unsymmetrical 2,3-azacyclic counterparts have remained underexplored. In the present study, we report density functional theory studies investigating the structure of such unsymmetrical azacyclic allenes and experimental efforts to access and engage them in strain-promoted cycloadditions under mild conditions. Control experiments support either concerted or stepwise diradical mechanisms for these reactions, depending on the type of cycloaddition examined. Moreover, we generate the corresponding 2,3-oxacyclic allene and demonstrate its reactivity in cycloadditions and a metal-catalysed process. Given the scaffolds accessed, coupled with the observed selectivity trends, these results are expected to encourage the application of unsymmetrical heterocyclic allenes for the synthesis of heterocycles that bear a high fraction of sp3-hybridized atoms.
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Affiliation(s)
- Andrew V. Kelleghan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Arismel Tena Meza
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Neil K. Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
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8
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Tang Y, Shi W, Du J, Ren Y, Xiao Y, Guo H. Diastereoselective Synthesis of Allenes through Phosphine-Catalyzed Cascade Isomerization/Annulation. Org Lett 2023. [PMID: 38019529 DOI: 10.1021/acs.orglett.3c03283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2023]
Abstract
Phosphine-catalyzed cascade isomerization/annulation has been developed to realize a diastereoselective synthesis of allenes installed on the hexahydropentalene skeleton, which contains five chiral centers (and one axial chirality). This reaction tolerated a broad range of allenoates and enynes. The allene products were transformed to various halogen-substituted fused-ring compounds.
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Affiliation(s)
- Yi Tang
- Department of Chemistry and Innovation Center of Pesticide Research, China Agricultural University, Beijing 100193, P. R. China
| | - Wangyu Shi
- Department of Chemistry and Innovation Center of Pesticide Research, China Agricultural University, Beijing 100193, P. R. China
| | - Juan Du
- Department of Chemistry and Innovation Center of Pesticide Research, China Agricultural University, Beijing 100193, P. R. China
| | - Yue Ren
- Department of Chemistry and Innovation Center of Pesticide Research, China Agricultural University, Beijing 100193, P. R. China
| | - Yumei Xiao
- Department of Chemistry and Innovation Center of Pesticide Research, China Agricultural University, Beijing 100193, P. R. China
| | - Hongchao Guo
- Department of Chemistry and Innovation Center of Pesticide Research, China Agricultural University, Beijing 100193, P. R. China
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9
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Jankovic CL, McIntosh KC, Lofstrand VA, West FG. Stereoselective Intramolecular [2+2] Trapping of 1,2-Cyclohexadienes: a Route to Rigid, Angularly Fused Tricyclic Scaffolds. Chemistry 2023; 29:e202301668. [PMID: 37352092 DOI: 10.1002/chem.202301668] [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: 06/15/2023] [Revised: 06/22/2023] [Accepted: 06/23/2023] [Indexed: 06/25/2023]
Abstract
1,2-Cyclohexadienes generated under mild fluoride-mediated desilylative conditions undergo efficient intramolecular [2+2] trapping, providing tricyclic alkylidene cyclobutanes with complete diastereoselectivity for the cis-fused products. Pendent styrenes or electron-deficient olefins can trap simple 1,2-cyclohexadienes or their oxygenated counterparts, with 14 substrates being disclosed. Reactions proceed at ambient temperature using just cesium fluoride in up to 91 % yield, and the necessary precursors are easily accessed from substituted 2-bromocyclohexenones. Multiple synthetic routes have been developed to install the appropriate functional groups required for [2+2] trapping.
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Affiliation(s)
| | - Kyle C McIntosh
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada
| | - Verner A Lofstrand
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada
| | - F G West
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada
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10
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Mehta MM, Gonzalez JAM, Bachman JL, Garg NK. Cyclic Allene Approach to the Manzamine Alkaloid Keramaphidin B. Org Lett 2023; 25:5553-5557. [PMID: 37387644 PMCID: PMC10460088 DOI: 10.1021/acs.orglett.3c01489] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/01/2023]
Abstract
We report an approach to the core of the manzamine alkaloid keramaphidin B that relies on the strain-promoted cycloaddition of an azacyclic allene with a pyrone trapping partner. The cycloaddition is tolerant of nitrile and primary amide functional groups and can be complemented with a subsequent retro-Diels-Alder step. These efforts demonstrate that strained cyclic allenes can be used to build significant structural complexity and should encourage further studies of these fleeting intermediates.
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Affiliation(s)
- Milauni M Mehta
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
| | - Jordan A M Gonzalez
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
| | - James L Bachman
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
| | - Neil K Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
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11
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Witkowski DC, McVeigh MS, Scherer GM, Anthony SM, Garg NK. Catalyst-Controlled Annulations of Strained Cyclic Allenes with π-Allylpalladium Complexes. J Am Chem Soc 2023; 145:10491-10496. [PMID: 37141000 PMCID: PMC10460090 DOI: 10.1021/jacs.3c03102] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Strained cyclic allenes are a class of in situ-generated fleeting intermediates that, despite being discovered more than 50 years ago, has received significantly less attention from the synthetic community compared to related strained intermediates. Examples of trapping strained cyclic allenes that involve transition metal catalysis are especially rare. We report the first annulations of highly reactive cyclic allenes with in situ-generated π-allylpalladium species. By varying the ligand employed, either of two isomeric polycyclic scaffolds can be obtained with high selectivity. The products are heterocyclic and sp3-rich and bear two or three new stereocenters. This study should encourage the further development of fragment couplings that rely on transition metal catalysis and strained cyclic allenes for the rapid assembly of complex scaffolds.
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Affiliation(s)
- Dominick C Witkowski
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Matthew S McVeigh
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Georgia M Scherer
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Sarah M Anthony
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Neil K Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
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12
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Ippoliti FM, Adamson NJ, Wonilowicz LG, Nasrallah DJ, Darzi ER, Donaldson JS, Garg NK. Total synthesis of lissodendoric acid A via stereospecific trapping of a strained cyclic allene. Science 2023; 379:261-265. [PMID: 36656952 PMCID: PMC10462259 DOI: 10.1126/science.ade0032] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 11/18/2022] [Indexed: 01/21/2023]
Abstract
Small rings that contain allenes are unconventional transient compounds that have been known since the 1960s. Despite being discovered around the same time as benzyne and offering a number of synthetically advantageous features, strained cyclic allenes have seen relatively little use in chemical synthesis. We report a concise total synthesis of the manzamine alkaloid lissodendoric acid A, which hinges on the development of a regioselective, diastereoselective, and stereospecific trapping of a fleeting cyclic allene intermediate. This key step swiftly assembles the azadecalin framework of the natural product, allows for a succinct synthetic endgame, and enables a 12-step total synthesis (longest linear sequence; 0.8% overall yield). These studies demonstrate that strained cyclic allenes are versatile building blocks in chemical synthesis.
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Affiliation(s)
| | | | - Laura G. Wonilowicz
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Daniel J. Nasrallah
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | | | | | - Neil K. Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
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13
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Bora J, Dutta M, Chetia B. Cobalt catalyzed alkenylation/annulation reactions of alkynes via C–H activation: A review. Tetrahedron 2023. [DOI: 10.1016/j.tet.2023.133248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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14
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Abstract
Strained intermediates such as cyclic alkynes and allenes are most commonly utilized in nucleophilic additions and cycloadditions, but have seen increased use in a third area of reactivity: metal-mediated transformations. The merger of strained intermediates and metal catalysis has enabled rapid access to complex, polycyclic systems. Following a discussion of relevant landmark studies involving metals and strained intermediates, this article highlights recent advances in transition metal-mediated transformations from our laboratory. Specifically, this includes the use of arynes in the synthesis of decorated organometallic complexes, and the utilization of cyclic allenes to access enantioenriched heterocycles. Moreover, the broad applicability of such transformations, and exciting future areas of research are discussed.
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Affiliation(s)
- Katie A. Spence
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
- These authors contributed equally: Katie A. Spence and Arismel Tena Meza
| | - Arismel Tena Meza
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
- These authors contributed equally: Katie A. Spence and Arismel Tena Meza
| | - Neil K. Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
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15
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Spence KA, Chari JV, Di Niro M, Susick RB, Ukwitegetse N, Djurovich PI, Thompson ME, Garg NK. π-Extension of heterocycles via a Pd-catalyzed heterocyclic aryne annulation: π-extended donors for TADF emitters. Chem Sci 2022; 13:5884-5892. [PMID: 35685807 PMCID: PMC9132060 DOI: 10.1039/d2sc01788a] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 05/03/2022] [Indexed: 11/21/2022] Open
Abstract
We report the annulation of heterocyclic building blocks to access π-extended polycyclic aromatic hydrocarbons (PAHs). The method involves the trapping of short-lived hetarynes with catalytically-generated biaryl palladium intermediates and allows for the concise appendage of three or more fused aromatic rings about a central heterocyclic building block. Our studies focus on annulating the indole and carbazole heterocycles through the use of indolyne and carbazolyne chemistry, respectively, the latter of which required the synthesis of a new carbazolyne precursor. Notably, these represent rare examples of transition metal-catalyzed reactions of N-containing hetarynes. We demonstrate the utility of our methodology in the synthesis of heterocyclic π-extended PAHs, which were then applied as ligands in two-coordinate metal complexes. As a result of these studies, we identified a new thermally-activated delayed fluorescence (TADF) emitter that displays up to 81% photoluminescence efficiency, along with insight into structure-property relationships. These studies underscore the utility of heterocyclic strained intermediates in the synthesis and study of organic materials.
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Affiliation(s)
- Katie A Spence
- Department of Chemistry and Biochemistry, University of California at Los Angeles Los Angeles California 90095 USA
| | - Jason V Chari
- Department of Chemistry and Biochemistry, University of California at Los Angeles Los Angeles California 90095 USA
| | - Mattia Di Niro
- Department of Chemistry, University of Southern California Los Angeles California 90089 USA
| | - Robert B Susick
- Department of Chemistry and Biochemistry, University of California at Los Angeles Los Angeles California 90095 USA
| | - Narcisse Ukwitegetse
- Department of Chemistry, University of Southern California Los Angeles California 90089 USA
| | - Peter I Djurovich
- Department of Chemistry, University of Southern California Los Angeles California 90089 USA
| | - Mark E Thompson
- Department of Chemistry, University of Southern California Los Angeles California 90089 USA
| | - Neil K Garg
- Department of Chemistry and Biochemistry, University of California at Los Angeles Los Angeles California 90095 USA
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16
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Vaith J, Rodina D, Spaulding GC, Paradine SM. Pd-Catalyzed Heteroannulation Using N-Arylureas as a Sterically Undemanding Ligand Platform. J Am Chem Soc 2022; 144:6667-6673. [PMID: 35380831 PMCID: PMC9026275 DOI: 10.1021/jacs.2c01019] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Indexed: 12/03/2022]
Abstract
We report the development of ureas as sterically undemanding pro-ligands for Pd catalysis. N-Arylureas outperform phosphine ligands for the Pd-catalyzed heteroannulation of N-tosyl-o-bromoanilines and 1,3-dienes, engaging diverse coupling partners for the preparation of 2-subsituted indolines, including sterically demanding substrates that have not previously been tolerated. Experimental and computational studies on model Pd-urea and Pd-ureate complexes are consistent with monodentate binding through the nonsubstituted nitrogen, which is uncommon for metal-ureate complexes.
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Affiliation(s)
- Jakub Vaith
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Dasha Rodina
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Gregory C. Spaulding
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Shauna M. Paradine
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
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17
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Abstract
Transient strained cyclic intermediates, such as strained cyclic allenes, are useful building blocks for the synthesis of structurally and stereochemically complex scaffolds. Trappings of strained cyclic allenes are thought to occur primarily through either two or one electron processes. Regarding the latter, diradical intermediates have been invoked in (2 + 2) cycloadditions and (3 + 2) nitrone cycloadditions. The present study questions if a monoradical pathway could exist for strained cyclic allene reactivity, as examined in the reaction of 1,2-cyclohexadiene and TEMPO radical. Our findings suggest the viability of this monoradical pathway.
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Affiliation(s)
- Matthew S. McVeigh
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, United States
| | - Neil K. Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, United States
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18
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Chen L, Lin C, Zhang S, Zhang X, Zhang J, Xing L, Guo Y, Feng J, Gao J, Du D. 1,4-Alkylcarbonylation of 1,3-Enynes to Access Tetra-Substituted Allenyl Ketones via an NHC-Catalyzed Radical Relay. ACS Catal 2021. [DOI: 10.1021/acscatal.1c03861] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Lei Chen
- Department of Organic Chemistry, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Chen Lin
- Department of Organic Chemistry, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Simiao Zhang
- Department of Organic Chemistry, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Xiaojin Zhang
- Department of Organic Chemistry, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Jianming Zhang
- Department of Organic Chemistry, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Lianjie Xing
- Department of Organic Chemistry, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Yage Guo
- Department of Organic Chemistry, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Jie Feng
- Department of Organic Chemistry, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Jian Gao
- Department of Organic Chemistry, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Ding Du
- Department of Organic Chemistry, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, P. R. China
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Anthony S, Wonilowicz LG, McVeigh MS, Garg NK. Leveraging Fleeting Strained Intermediates to Access Complex Scaffolds. JACS AU 2021; 1:897-912. [PMID: 34337603 PMCID: PMC8317162 DOI: 10.1021/jacsau.1c00214] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Indexed: 05/07/2023]
Abstract
Arynes, strained cyclic alkynes, and strained cyclic allenes were validated as plausible intermediates in the 1950s and 1960s. Despite initially being considered mere scientific curiosities, these transient and highly reactive species have now become valuable synthetic building blocks. This Perspective highlights recent advances in the field that have allowed access to structural and stereochemical complexity, including recent breakthroughs in asymmetric catalysis.
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