1
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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 DOI: 10.1021/jacs.4c03369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [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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2
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Wee MYS, Quek S, Wu CS, Su MD, So CW. Isolable Spirocyclic Silylone: π-Delocalized Spiro[3.3]heptasila-2,6-diylidone. J Am Chem Soc 2024; 146:14410-14415. [PMID: 38754079 DOI: 10.1021/jacs.4c02807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Strained cyclic tetrylones are important synthons due to various synthetic applications. Connecting two cyclic tetrylone rings through a single shared quaternary group 14 element atom to form a spirocyclic molecule has been unexplored both theoretically and experimentally. The formation of a spirocyclic motif has been a synthetic challenge. In contrast, the reaction of amidinato disilicon(I) 1, (Me3P)2SiCl4, and KC8 afforded π-delocalized spiro[3.3]heptasila-2,6-diylidone2 and tetrasilacyclobutadiene byproducts 3 and 4. Compound 2 is the smallest spirocyclic tetrylone derivative, which is composed of a σ-type lone pair and delocalized π bond in each all-silicon spirocyclic ring. The electronic property is supported by its coordination with a W(CO)5 moiety.
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Affiliation(s)
- Meldon Yi-Shuo Wee
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 637371 Singapore
| | - Shina Quek
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 637371 Singapore
| | - Chi-Shiun Wu
- Department of Applied Chemistry, National Chiayi University, Chiayi 60004, Taiwan
| | - Ming-Der Su
- Department of Applied Chemistry, National Chiayi University, Chiayi 60004, Taiwan
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Cheuk-Wai So
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 637371 Singapore
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3
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de Carvalho RL, Wood JM, Almeida RG, Berry NG, da Silva Júnior EN, Bower JF. The Synthesis and Reactivity of Naphthoquinonynes. Angew Chem Int Ed Engl 2024; 63:e202400188. [PMID: 38445547 DOI: 10.1002/anie.202400188] [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: 01/03/2024] [Revised: 03/01/2024] [Accepted: 03/04/2024] [Indexed: 03/07/2024]
Abstract
The first systematic exploration of the synthesis and reactivity of naphthoquinonynes is described. Routes to two regioisomeric Kobayashi-type naphthoquinonyne precursors have been developed, and the reactivity of the ensuing 6,7- and 5,6-aryne intermediates has been investigated. Remarkably, these studies have revealed that a broad range of cycloadditions, nucleophile additions and difunctionalizations can be achieved while maintaining the integrity of the highly sensitive quinone unit. The methodologies offer a powerful diversity oriented approach to C6 and C7 functionalized naphthoquinones, which are typically challenging to access. From a reactivity viewpoint, the study is significant because it demonstrates that aryne-based functionalizations can be utilized strategically in the presence of highly reactive and directly competing functionality.
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Affiliation(s)
- Renato L de Carvalho
- Instituto de Ciências Exatas, Departamento de Química, Universidade Federal de Minas Gerais - UFMG, 31270-901, Belo, Horizonte - MG, Brazil
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, United Kingdom
| | - James M Wood
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, United Kingdom
- The Ferrier Research Institute, Victoria University of Wellington, Wellington, 6012, New Zealand
| | - Renata G Almeida
- Instituto de Ciências Exatas, Departamento de Química, Universidade Federal de Minas Gerais - UFMG, 31270-901, Belo, Horizonte - MG, Brazil
| | - Neil G Berry
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, United Kingdom
| | - Eufrânio N da Silva Júnior
- Instituto de Ciências Exatas, Departamento de Química, Universidade Federal de Minas Gerais - UFMG, 31270-901, Belo, Horizonte - MG, Brazil
| | - John F Bower
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, United Kingdom
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, United Kingdom
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4
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Kevorkian PV, Sneddon DS, Ritts CB, Hoye TR. Phosphorane-Promoted C-C Coupling during Aryne Annulations. Angew Chem Int Ed Engl 2024; 63:e202318774. [PMID: 38324736 PMCID: PMC11002863 DOI: 10.1002/anie.202318774] [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: 12/06/2023] [Revised: 01/13/2024] [Accepted: 01/15/2024] [Indexed: 02/09/2024]
Abstract
Arynes are fleeting, high-energy intermediates that undergo myriad trapping reactions by nucleophiles. Their unusual reactivity compared to other electrophiles can spur unexpected mechanistic pathways enroute to the formation of benzenoid products. Herein we explore a particularly unique case of thermally generated arynes reacting with phosphoranes to form helical dibenzothiophenes and -selenophenes. Multiple new helical polycyclic aromatic products are reported. DP4+ and X-ray crystallographic analysis were used in tandem to confirm the structural topologies of selected products and to demonstrate the utility of DP4+ for distinguishing between isomeric polycyclic aromatic compounds. Lastly, we discuss a plausible mechanism consistent with DFT computations that accounts for the product formation; namely, ligand coupling (i.e., reductive elimination) within a hypervalent, pentacarbon-ligated σ-phosphorane furnishes the dibenzothio- or dibenzoselenophene.
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Affiliation(s)
- Paul V Kevorkian
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
| | - Dorian S Sneddon
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
| | - Casey B Ritts
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
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5
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Yan Q, Zhuang Z, Fan R, Wang J, Yao T, Tan J. Access to N-Aryl (Iso)quinolones via Aryne-Induced Three-Component Coupling Reaction. Org Lett 2024; 26:1840-1844. [PMID: 38412291 DOI: 10.1021/acs.orglett.3c04385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
N-Aryl (iso)quinolones are of increasing interest in material and medicinal chemistry, although general routes for their provision remain underexplored, especially when compared with its N-alkyl counterparts. Herein, we report a modular and transition-metal-free, aryne-induced three-component coupling protocol that allows the facile synthesis of structurally diverse N-aryl (iso)quinolones from readily accessible halo-(iso)quinolines in the presence of water. Preliminary results highlight the applicability of our method through scale-up synthesis, downstream derivatization, and flexible synthesis involving other types of aryne precursors.
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Affiliation(s)
- Qiang Yan
- College of Chemistry, Beijing University of Chemical Technology (BUCT), Beijing 100029, China
- College of Chemistry and Chemical Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China
| | - Zhe Zhuang
- College of Chemistry, Beijing University of Chemical Technology (BUCT), Beijing 100029, China
| | - Rong Fan
- College of Chemistry, Beijing University of Chemical Technology (BUCT), Beijing 100029, China
| | - Jingwen Wang
- College of Chemistry, Beijing University of Chemical Technology (BUCT), Beijing 100029, China
| | - Tuanli Yao
- College of Chemistry and Chemical Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China
| | - Jiajing Tan
- College of Chemistry, Beijing University of Chemical Technology (BUCT), Beijing 100029, China
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6
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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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7
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Barnå F, Hribersek M, Orthaber A, Pilarski LT. Synthesis and crystal structures of boryl ortho-silylaryl tri-fluoro-methane-sulfonates. Acta Crystallogr E Crystallogr Commun 2024; 80:143-147. [PMID: 38333140 PMCID: PMC10848976 DOI: 10.1107/s2056989024000264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 01/08/2024] [Indexed: 02/10/2024]
Abstract
We report the synthesis and structural characterization of three crystalline borylated ortho-silylaryl tri-fluoro-methane-sulfonates: 5-(4,4,5,5-tetra-methyl-1,3,2-dioxaborolan-2-yl)-2-(tri-methyl-sil-yl)phenyl tri-fluoro-methane-sulfonate, C16H24BF3O5SSi (1a), 4-(4,4,5,5-tetra-methyl-1,3,2-dioxaborolan-2-yl)-2-(tri-methyl-sil-yl)phenyl tri-fluoro-methane-sulfonate, C16H24BF3O5SSi (1b), and 2-methyl-4-(4,4,5,5-tetra-methyl-1,3,2-dioxaborolan-2-yl)-6-(tri-methyl-silyl)phen-yl tri-fluoro-methane-sulfonate, C17H26BF3O5SSi (2), which are versatile aryne precursors. For all three compounds, the heteroatom substituents are almost coplanar with the central aromatic moiety. C-heteroatom bonding metrics are unexceptional and fall withing the typical range of C-B, C-Si, and C-O single bonds. Despite numerous electronegative sites, only weak inter-molecular inter-actions are observed in the solid state.
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Affiliation(s)
- Fredrik Barnå
- Department of Chemistry-BMC, Uppsala University, Box 576, 75123, Uppsala, Sweden
| | - Matic Hribersek
- Department of Chemistry-BMC, Uppsala University, Box 576, 75123, Uppsala, Sweden
| | - Andreas Orthaber
- Uppsala University Ångström Laboratories, Box 523, 75120 Uppsala, Sweden
| | - Lukasz T. Pilarski
- Department of Chemistry-BMC, Uppsala University, Box 576, 75123, Uppsala, Sweden
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8
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Abstract
The concept of strain in organic compounds is as old as modern organic chemistry and was initially introduced to justify the synthetic setbacks along the synthesis of small ring systems (pars construens of strain). In the last decades, chemists have developed an arsenal of strain-release reactions (pars destruens of strain) which can generate─with significant driving force─rigid aliphatic systems that can act as three-dimensional alternatives to (hetero)arenes. Photocatalysis added an additional dimension to strain-release processes by leveraging the energy of photons to create chemical complexity under mild conditions. This perspective presents the latest advancements in strain-release photocatalysis─with emphases on mechanisms, catalytic cycles, and current limitations─the unique chemical architectures that can be produced, and possible future directions.
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Affiliation(s)
- Peter Bellotti
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
- Department of Pharmacology, Weill Cornell Medicine, 1300 York Avenue, New York 10021, New York United States
| | - Frank Glorius
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
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9
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Chen J, Liu S, Su S, Fan R, Zhang R, Meng W, Tan J. Sulfonium-based precise alkyl transposition reactions. SCIENCE ADVANCES 2023; 9:eadi1370. [PMID: 37713480 PMCID: PMC10881050 DOI: 10.1126/sciadv.adi1370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 08/14/2023] [Indexed: 09/17/2023]
Abstract
S-adenosyl-L-methionine (SAM), a sulfonium-based cofactor, plays an important role in numerous biological processes as methyl donor. Inspired by the function of sulfonium motif in this nature's synthetic toolkit, we here present an aryne-activation strategy that the sulfonium intermediates in situ generated from thioethers display unique reactivity toward alkyl group transposition. Experimental and theoretical studies indicate that the reaction occurs in an intermolecular fashion where the TfO--incorporated [K(18-crown-6)] complex acts as a key promoter for this thermodynamically favored process. Next, a series of robust, easy-to-prepare sulfonium salts are designed and developed as electrophilic alkylation reagents accordingly. Both systems feature for broad scope, excellent selectivity, and simple operation. Moreover, we highlight the synthetic value through molecular editing and late-stage modification of complex scaffolds or even active pharmaceutical ingredients.
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Affiliation(s)
- Jian Chen
- Department of Organic Chemistry, College of Chemistry, Beijing University of Chemical Technology (BUCT), Beijing 100029, China
| | - Shilu Liu
- Department of Organic Chemistry, College of Chemistry, Beijing University of Chemical Technology (BUCT), Beijing 100029, China
| | - Shuaisong Su
- Department of Organic Chemistry, College of Chemistry, Beijing University of Chemical Technology (BUCT), Beijing 100029, China
| | - Rong Fan
- Department of Organic Chemistry, College of Chemistry, Beijing University of Chemical Technology (BUCT), Beijing 100029, China
| | - Ruirui Zhang
- Department of Organic Chemistry, College of Chemistry, Beijing University of Chemical Technology (BUCT), Beijing 100029, China
| | - Wei Meng
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiajing Tan
- Department of Organic Chemistry, College of Chemistry, Beijing University of Chemical Technology (BUCT), Beijing 100029, China
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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: 0] [Impact Index Per Article: 0] [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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Darzi ER, Stanfield DA, McDermott L, Kelleghan AV, Schwartz BJ, Garg NK. Facile synthesis of 2-aza-9,10-diphenylanthracene and the effect of precise nitrogen atom incorporation on OLED emitters performance. MATERIALS ADVANCES 2023; 4:3351-3355. [PMID: 37588776 PMCID: PMC10388396 DOI: 10.1039/d3ma00280b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 07/12/2023] [Indexed: 08/18/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are important compounds in materials chemistry, particularly for optoelectronic applications. One strategy for tuning PAH properties involves the net exchange of carbon atoms for heteroatoms, such as nitrogen. We report a comparative study of the well-known fluorophore 9,10-diphenylanthracene with an aza analog. The latter compound is accessed using a short sequence involving the use of two strained cyclic alkynes, benzyne and a 3,4-piperidyne, in Diels-Alder cycloaddition sequences. Comparative studies of 9,10-diphenylanthracene and the aza-analog show how the addition of a single nitrogen atom impacts electrochemical and optical properties. Organic light-emitting diode (OLED) devices were prepared using both compounds, which showed that nitrogen substitution leads to an unexpected red shift in electroluminescence, likely due to exciplex formation between the active layer and the 4,4'-N,N'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB) hole-transport layer. These studies highlight a unique approach to accessing heteroatom-containing PAHs, while underscoring the impact of heteroatoms on OLED device performance.
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Affiliation(s)
- Evan R Darzi
- Department of Chemistry and Biochemistry, University of California at Los Angeles Los Angeles California 90095 USA
| | - Dane A Stanfield
- Department of Chemistry and Biochemistry, University of California at Los Angeles Los Angeles California 90095 USA
| | - Luca McDermott
- Department of Chemistry and Biochemistry, University of California at Los Angeles Los Angeles California 90095 USA
| | - Andrew V Kelleghan
- Department of Chemistry and Biochemistry, University of California at Los Angeles Los Angeles California 90095 USA
| | - Benjamin J Schwartz
- Department of Chemistry and Biochemistry, University of California at Los Angeles Los Angeles California 90095 USA
| | - Neil K Garg
- Department of Chemistry and Biochemistry, University of California at Los Angeles Los Angeles California 90095 USA
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12
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Spence KA, Hoffmann M, Garg NK. Total Synthesis of Phenanthroindolizidines Using Strained Azacyclic Alkynes. Org Lett 2023; 25:5044-5048. [PMID: 37379230 PMCID: PMC10460089 DOI: 10.1021/acs.orglett.3c01740] [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: 06/30/2023]
Abstract
We report a concise approach to phenanthroindolizidine alkaloids, wherein strained azacyclic alkynes are intercepted in Pd-catalyzed annulations. Two types of strained intermediates were evaluated: a functionalized piperidyne and a new strained intermediate, an indolizidyne. We show that each can be employed, ultimately allowing access to three natural products: tylophorine, tylocrebine, and isotylocrebine. These efforts demonstrate the successful merger of strained azacyclic alkyne chemistry with transition-metal catalysis for the construction of complex heterocycles.
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Affiliation(s)
- Katie A Spence
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
| | - Marie Hoffmann
- 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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13
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Kelleghan AV, Bulger AS, Witkowski DC, Garg NK. Strain-promoted reactions of 1,2,3-cyclohexatriene and its derivatives. Nature 2023; 618:748-754. [PMID: 37075803 PMCID: PMC10460091 DOI: 10.1038/s41586-023-06075-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 04/12/2023] [Indexed: 04/21/2023]
Abstract
Since 18251, compounds with the molecular formula C6H6-most notably benzene-have been the subject of rigorous scientific investigation2-7. Of these compounds, 1,2,3-cyclohexatriene has been largely overlooked. This strained isomer is substantially (approximately 100 kcal mol-1) higher in energy compared with benzene and, similar to its relatives benzyne and 1,2-cyclohexadiene, should undergo strain-promoted reactions. However, few experimental studies of 1,2,3-cyclohexatriene are known8-12. Here we demonstrate that 1,2,3-cyclohexatriene and its derivatives participate in a host of reaction modes, including diverse cycloadditions, nucleophilic additions and σ-bond insertions. Experimental and computational studies of an unsymmetrical derivative of 1,2,3-cyclohexatriene demonstrate the potential for highly selective reactions of strained trienes despite their high reactivity and short lifetimes. Finally, the integration of 1,2,3-cyclohexatrienes into multistep syntheses demonstrates their use in rapidly assembling topologically and stereochemically complex molecules. Collectively, these efforts should enable further investigation of the strained C6H6 isomer 1,2,3-cyclohexatriene and its derivatives, as well as their application in the synthesis of important compounds.
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Affiliation(s)
- Andrew V Kelleghan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Ana S Bulger
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Dominick C Witkowski
- 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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14
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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: 7] [Impact Index Per Article: 7.0] [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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15
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Fan R, Liu S, Yan Q, Wei Y, Wang J, Lan Y, Tan J. Empowering boronic acids as hydroxyl synthons for aryne induced three-component coupling reactions. Chem Sci 2023; 14:4278-4287. [PMID: 37123174 PMCID: PMC10132127 DOI: 10.1039/d3sc00072a] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 03/13/2023] [Indexed: 03/16/2023] Open
Abstract
Boronic acids have become one of the most prevalent classes of reagents in modern organic synthesis, displaying various reactivity profiles via C-B bond cleavage. Herein, we describe the utilization of a readily available boronic acid as an efficient surrogate of hydroxide upon activation via fluoride complexation. The hitherto unknown aryne induced ring-opening reaction of cyclic sulfides and three-component coupling of fluoro-azaarenes are developed to exemplify the application value. Different from metal hydroxides or water, this novel hydroxy source displays mild activation conditions, great functionality tolerance and structural tunability, which shall engender a new synthetic paradigm and in a broad context offer new blueprints for organoboron chemistry. Detailed computational studies also recognize the fluoride activation mode, provide in-depth insights into the unprecedented mechanistic pathway and elucidate the reactivity difference of ArB(OH) x F y complexes, which fully support the experimental data.
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Affiliation(s)
- Rong Fan
- Department of Organic Chemistry, Beijing University of Chemical Technology Beijing 100029 China
| | - Shihan Liu
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University Chongqing 400030 China
| | - Qiang Yan
- Department of Organic Chemistry, Beijing University of Chemical Technology Beijing 100029 China
| | - Yun Wei
- Department of Organic Chemistry, Beijing University of Chemical Technology Beijing 100029 China
| | - Jingwen Wang
- Department of Organic Chemistry, Beijing University of Chemical Technology Beijing 100029 China
| | - Yu Lan
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University Chongqing 400030 China
- ZhengZhou JiShu Institute of AI Science Zhengzhou 450000 China
| | - Jiajing Tan
- Department of Organic Chemistry, Beijing University of Chemical Technology Beijing 100029 China
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16
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Kamikawa K. Asymmetric reactions involving aryne intermediates. Nat Rev Chem 2023:10.1038/s41570-023-00485-y. [PMID: 37117814 DOI: 10.1038/s41570-023-00485-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2023] [Indexed: 04/03/2023]
Abstract
Although arynes are usually considered fleeting intermediates, they are highly valuable synthons because they enable the introduction of aromatic rings and the simultaneous formation of new bonds at two sites. Although catalytic reactions using transition metals are excellent method for constructing complex polycyclic aromatic molecules in a single step, the use of asymmetric catalysis for the capture of arynes remains a crucial goal for the progress of aryne chemistry. Catalytic asymmetric reactions of arenes are challenging, requiring sufficient interactions between the neutral and highly reactive short-lived aryne intermediates in a stereo-controlled fashion. In addition, spontaneous decomposition, as well as side reactions, has hindered their development and, until recently, highly enantioselective reactions using arynes had remained elusive. This Review highlights asymmetric reactions using arynes, featuring diastereoselective, enantioselective and catalytic enantioselective reactions.
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17
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Li Q, Hua Y, Tang C, Chen D, Luo M, Xia H. Isolation, Reactivity, and Tunable Properties of a Strained Antiaromatic Osmacycle. J Am Chem Soc 2023; 145:7580-7591. [PMID: 36952602 DOI: 10.1021/jacs.3c00942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
Strain and antiaromaticity in compounds are recognized as two substantial destabilizing features, and consequently, realization of dual destabilizing features in a single molecule is challenging and far more difficult in a single ring. Moreover, transformation of an antiaromatic framework to different antiaromatic or aromatic species is a significant subject in antiaromatic chemistry and has attracted increasing interest. In this work, we isolated a highly strained antiaromatic metallacycle in which a cyclic metal vinylidene unit is embedded. Computational studies revealed its ring strain energies and antiaromatic character and showed that the metal incorporation and the phosphonium substituents play a crucial role in its stabilization. The mechanism of its formation has been illustrated by density functional theory (DFT) calculations and the isolation of a key intermediate. We further discovered diverse reactivities and structural reshuffling of this unusual strained antiaromatic complex according to its two destabilizing characters. We obtained two isomers of metallaindenes fused with oxiranes from the direct oxidation of the metal vinylidene or by nucleophilic addition to an isolated metallacyclocumulene formed by the reaction of metal vinylidene with hydroxide ion, achieving a reconfiguration of the antiaromatic framework. Transformations of the antiaromatic metallacycle by electrophiles to various aromatic metallaindynes have been achieved, and that a condensed Fukui function was employed to confirm the regioselectivity of the electrophilic additions, and the acid/base-induced aromaticity switch along with tunable photophysical properties were investigated. These interesting transformations not only enrich the chemistry of metal vinylidenes and antiaromatics and could also perform potentially as switchable optical materials.
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Affiliation(s)
- Qian Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
| | - Yuhui Hua
- Shenzhen Grubbs Institute, Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Chun Tang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
| | - Dafa Chen
- Shenzhen Grubbs Institute, Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Ming Luo
- Shenzhen Grubbs Institute, Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Haiping Xia
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
- Shenzhen Grubbs Institute, Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
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18
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Tian H, Zhang L. Total synthesis of lissodendoric acid A by [4 + 2] cycloaddition of transient cyclic allene. Chin J Nat Med 2023; 21:161-162. [PMID: 37003638 DOI: 10.1016/s1875-5364(23)60417-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Indexed: 04/03/2023]
Affiliation(s)
- Hongchang Tian
- Department of Pharmaceutical Botany, School of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Lei Zhang
- Department of Pharmaceutical Botany, School of Pharmacy, Naval Medical University, Shanghai 200433, China.
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19
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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: 0] [Impact Index Per Article: 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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20
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Jankovic CL, West FG. 2 + 2 Trapping of Acyloxy-1,2-cyclohexadienes with Styrenes and Electron-Deficient Olefins. Org Lett 2022; 24:9497-9501. [PMID: 36519787 DOI: 10.1021/acs.orglett.2c03978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Oxygenated-1,2-cyclohexadienes and their unsubstituted counterpart can be generated under mild conditions by fluoride-induced desilylation and undergo intermolecular [2 + 2]-cycloaddition reactions with a variety of alkene traps to afford bicyclo[4.2.0]octenes. Both styrenes and electron-deficient olefins react in good conversion and with complete regioselectivity in favor of cyclobutane formation at the unsubstituted C2/C3 carbons of the C1-substituted cyclic allenes. Diastereoselectivities are modest (1.1-5.7:1) with a preference for the exo-isomer.
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Affiliation(s)
- Christian L Jankovic
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - F G West
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
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21
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Whole-cell biocatalyzed organic solvent-free conversion of dill oil to cis-(-)-dihydrocarvone rich aromatic hydrosol: Chemical and aroma profiling. Process Biochem 2022. [DOI: 10.1016/j.procbio.2022.08.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Hancock SN, Yuntawattana N, Valdez SM, Michaudel Q. Expedient Synthesis and Ring-Opening Metathesis Polymerization of Pyridinonorbornenes. Polym Chem 2022; 13:5530-5535. [PMID: 37193226 PMCID: PMC10168028 DOI: 10.1039/d2py00857b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pyridine-containing polymers are promising materials for a variety of applications from the capture of contaminants to the self-assembly of block copolymers. However, the innate Lewis basicity of the pyridine motif often hampers living polymerization catalyzed by transition-metal complexes. Herein, we report the expedient synthesis of pyridinonorbornene monomers via a [4+2] cycloaddition between 2,3-pyridynes and cyclopentadiene. Well-controlled ring-opening metathesis polymerization was enabled by careful structural design of the monomer. Polypyridinonorbornenes exhibited high Tg and Td, a promising feature for high-temperature applications. Investigation of the polymerization kinetics and of the reactivity of the chain ends shed light on the influence of nitrogen coordination on the chain-growth mechanism.
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Affiliation(s)
- Sarah N Hancock
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
| | - Nattawut Yuntawattana
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
- Present Address: Department of Materials Science, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Sara M Valdez
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
| | - Quentin Michaudel
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
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23
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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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24
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Shi B, Liu JB, Wang ZT, Wang L, Lan Y, Lu LQ, Xiao WJ. Synthesis of Chiral Endocyclic Allenes by Palladium-Catalyzed Asymmetric Annulation Followed by Cope Rearrangement. Angew Chem Int Ed Engl 2022; 61:e202117215. [PMID: 35333435 DOI: 10.1002/anie.202117215] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Indexed: 11/10/2022]
Abstract
Catalytic asymmetric synthesis of chiral endocyclic allenes remains a challenge in allene chemistry owing to unfavored tension and complex chirality. Here, we present a new relay strategy merging Pd-catalyzed asymmetric [3+2] annulation with enyne-Cope rearrangement, providing a facile route to chiral 9-membered endocyclic allenes with high efficiency and enantioselectivity. Moreover, theoretical calculations and experimental studies were performed to illustrate the critical, but unusual Cope rearrangement that allows for the complete central-to-axial chirality transfer.
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Affiliation(s)
- Bin Shi
- CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan, Hubei 430079, China
| | - Jia-Bin Liu
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou, 450001, China
| | - Ze-Tian Wang
- School of Chemical and Environmental Engineering, Jianghan University, Wuhan, 430056, China
| | - Liang Wang
- School of Chemical and Environmental Engineering, Jianghan University, Wuhan, 430056, China
| | - Yu Lan
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou, 450001, China
| | - Liang-Qiu Lu
- CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan, Hubei 430079, China.,State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics (LICP), Chinese Academy of Sciences, Lanzhou, 730000, P. R. China
| | - Wen-Jing Xiao
- CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan, Hubei 430079, China
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25
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Lu LQ, Shi B, Liu JB, Wang ZT, Wang L, Lan Y, Xiao WJ. Synthesis of Chiral Endocyclic Allenes by Palladium‐Catalyzed Asymmetric Annulation Followed by Cope Rearrangement. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202117215] [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)
- Liang-Qiu Lu
- Central China Normal University CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticides and Chemical Biology 152 Luoyu Road 430079 Wuhan, Hubei CHINA
| | - Bin Shi
- Central China Normal University College of Chemistry CHINA
| | - Jia-Bin Liu
- Zhengzhou University College of Chemistry CHINA
| | - Ze-Tian Wang
- Jianghan University School of Chemical and Environmental Engineering CHINA
| | - Liang Wang
- Jianghan University School of Chemical and Environmental Engineering CHINA
| | - Yu Lan
- Zhengzhou University College of Chemistry CHINA
| | - Wen-Jing Xiao
- Central China Normal University College of Chemistry CHINA
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26
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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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27
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Cho S, McLaren EJ, Wang Q. Three‐Component Difunctionalization of Cyclohexenyl Triflates: Direct Access to Versatile Cyclohexenes via Cyclohexynes. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202109482] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Seoyoung Cho
- Department of Chemistry Duke University Durham NC 27708 USA
| | - E. J. McLaren
- Department of Chemistry Duke University Durham NC 27708 USA
| | - Qiu Wang
- Department of Chemistry Duke University Durham NC 27708 USA
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28
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Cho S, McLaren EJ, Wang Q. Three-Component Difunctionalization of Cyclohexenyl Triflates: Direct Access to Versatile Cyclohexenes via Cyclohexynes. Angew Chem Int Ed Engl 2021; 60:26332-26336. [PMID: 34644004 DOI: 10.1002/anie.202109482] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/27/2021] [Indexed: 11/06/2022]
Abstract
Difunctionalization of strained cyclic alkynes presents a powerful strategy to build richly functionalized cyclic alkenes in an expedient fashion. Herein we disclose an efficient and flexible approach to achieve carbohalogenation, dicarbofunctionalization, aminohalogenation and aminocarbonation of readily available cyclohexenyl triflates. We have demonstrated the novel use of zincate base/nucleophile system for effective formation of key cyclohexyne intermediates and selective addition of various carbon and nitrogen nucleophiles. Importantly, leveraging the resulting organozincates enables the incorporation of a broad range of electrophilic partners to deliver structurally diverse cyclohexene motifs. The importance and utility of this method is also exemplified by the modularity of this approach and the ease in which even highly complex polycyclic scaffolds can be accessed in one step.
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Affiliation(s)
- Seoyoung Cho
- Department of Chemistry, Duke University, Durham, NC, 27708, USA
| | - E J McLaren
- Department of Chemistry, Duke University, Durham, NC, 27708, USA
| | - Qiu Wang
- Department of Chemistry, Duke University, Durham, NC, 27708, USA
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29
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Keck C, Hahn J, Gupta D, Bettinger HF. Solution Phase Reactivity of Dibenzo[c,e][1,2]azaborinine: Activation and Insertion into Si-E Single Bonds (E=H, OSi(CH 3 ) 3 , F, Cl) by a BN-Aryne. Chemistry 2021; 28:e202103614. [PMID: 34854508 PMCID: PMC9299606 DOI: 10.1002/chem.202103614] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Indexed: 11/24/2022]
Abstract
The boron‐nitrogen analogue of ortho‐benzyne, 1,2‐azaborinine, is a reactive intermediate that features a formal boron‐nitrogen triple bond. We here show by combining experimental and computational techniques that the Lewis acidity of the boron center of dibenzo[c,e][1,2]azaborinine allows interaction with the silicon containing single bonds Si−E through the silicon bonding partner E (E=F, Cl, OR, H). The binding to boron activates the Si−E bonds for subsequent insertion reaction. This shows that the BN‐aryne is a ferocious species that even can activate and insert into the very strong Si−F bond.
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Affiliation(s)
- Constanze Keck
- Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany
| | - Jennifer Hahn
- Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany
| | - Divanshu Gupta
- Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany
| | - Holger F Bettinger
- Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany
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30
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Bürger M, Ehrhardt N, Barber T, Ball LT, Namyslo JC, Jones PG, Werz DB. Phosphine-Catalyzed Aryne Oligomerization: Direct Access to α,ω-Bisfunctionalized Oligo( ortho-arylenes). J Am Chem Soc 2021; 143:16796-16803. [PMID: 34585921 DOI: 10.1021/jacs.1c08689] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A phosphine-catalyzed oligomerization of arynes using selenocyanates was developed. The use of JohnPhos as a bulky phosphine is the key to accessing α,ω-bisfunctionalized oligo(ortho-arylenes) with RSe as the substituent at one terminus and CN as the substituent at the other. The in situ formation of R3PSeR' cations, serving as sterically encumbered electrophiles, hinders the immediate reaction that affords the 1,2-bisfunctionalization product and instead opens a competitive pathway leading to oligomerization. Various optimized conditions for the predominant formation of dimers, but also for higher oligomers such as trimers and tetramers, were developed. Depending on the electronic properties of the electrophilic reaction partner, even compounds up to octamers were isolated. Optimization experiments revealed that a properly tuned phosphine as catalyst is of crucial importance. Mechanistic studies demonstrated that the cascade starts with the attack of cyanide; aryne insertion into n-mers leading to (n+1)-mers was ruled out.
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Affiliation(s)
| | | | - Thomas Barber
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Liam T Ball
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Jan C Namyslo
- Clausthal University of Technology, Institute of Organic Chemistry, Leibnizstrasse 6, 38678 Clausthal-Zellerfeld, Germany
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31
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Bro-Jørgensen W, Garner MH, Solomon GC. Quantification of the Helicality of Helical Molecular Orbitals. J Phys Chem A 2021; 125:8107-8115. [PMID: 34491758 PMCID: PMC8450904 DOI: 10.1021/acs.jpca.1c05799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The frontier molecular orbital (MO) topology of linear carbon molecules, such as polyynes, can be visually identified as helices. However, there is no clear way to quantify the helical curvature of these π-MOs, and it is thus challenging to quantify correlations between the helical curvature and molecular properties. In this paper, we develop a method that enables us to compute the helical curvature of MOs based on their nodal planes. Using this method, we define a robust way of quantifying the helical nature of MOs (helicality) by their deviation from a perfect helix. We explore several limiting cases, including polyynes, metallacumulenes, cyclic allenes, and spiroconjugated systems, where the change in helical curvature is subtle yet clearly highlighted with this method. For example, we show that strain only has a minor effect on the helicality of the frontier orbitals of cycloallenes and that the MOs of spiroconjugated systems are close to perfect helices around the spiro-carbon. Our work provides a well-defined method for assessing orbital helicality beyond visual inspection of MO isosurfaces, thus paving the way for future studies of how the helicality of π-MOs affects molecular properties.
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Affiliation(s)
- William Bro-Jørgensen
- Department of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Marc H Garner
- Department of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Gemma C Solomon
- Department of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
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32
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Kelleghan AV, Witkowski DC, McVeigh MS, Garg NK. Palladium-Catalyzed Annulations of Strained Cyclic Allenes. J Am Chem Soc 2021; 143:9338-9342. [PMID: 34143634 PMCID: PMC8290222 DOI: 10.1021/jacs.1c04896] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report Pd-catalyzed annulations of in situ generated strained cyclic allenes. This methodology employs aryl halides and cyclic allene precursors as the reaction partners in order to generate fused heterocyclic products. The annulation proceeds via the formation of two new bonds and an sp3 center. Moreover, both diastereo- and enantioselective variants of this methodology are validated, with the latter ultimately enabling the rapid enantioselective synthesis of a complex hexacyclic product. Studies leveraging transition metal catalysis to intercept cyclic allenes represent a departure from the more common, historical modes of cyclic allene trapping that rely on nucleophiles or cycloaddition partners. As such, this study is expected to fuel the development of reactions that strategically merge transition metal catalysis and transient strained intermediate chemistry for the synthesis of complex scaffolds.
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Affiliation(s)
- Andrew V Kelleghan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - 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
| | - Neil K Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
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