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Ippoliti FM, Wonilowicz LG, Adamson NJ, Darzi ER, Donaldson JS, Nasrallah DJ, Mehta MM, Kelleghan AV, Houk KN, Garg NK. Total Synthesis of Lissodendoric Acid A. Angew Chem Int Ed Engl 2024; 63:e202406676. [PMID: 38695853 DOI: 10.1002/anie.202406676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Indexed: 07/04/2024]
Abstract
We describe a full account of our synthetic strategy leading to the first total synthesis of the manzamine alkaloid lissodendoric acid A . These efforts demonstrate that strained cyclic allenes are valuable synthetic building blocks and can be employed efficiently in total synthesis.
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Affiliation(s)
- Francesca M Ippoliti
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Chemistry, Hamline University, St. Paul, Minnesota, 55104, USA
| | - Laura G Wonilowicz
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Nathan J Adamson
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA 94080, USA
| | - Evan R Darzi
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- ElectraTect, Inc., Phoenix, AZ 85004, USA
| | - Joyann S Donaldson
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Pfizer Oncology Medicinal Chemistry, San Diego, CA 92121, USA
| | - Daniel J Nasrallah
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Chemistry, Roanoke College, Salem, Virginia, 24153, USA
| | - Milauni M Mehta
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Small Molecule Therapeutic Discovery, Amgen Research, Amgen Inc., Thousand Oaks, CA 91320, USA
| | - Andrew V Kelleghan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Gilead Sciences Medicinal Chemistry, Foster City, CA 94404, USA
| | - K N Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Neil K Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
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2
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Xu Q, Hoye TR. Free carbenes from complementarily paired alkynes. Nat Chem 2024; 16:1083-1092. [PMID: 38918579 DOI: 10.1038/s41557-024-01550-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 05/02/2024] [Indexed: 06/27/2024]
Abstract
Carbenes (R1R2C:) like radicals, arynes and nitrenes constitute an important family of neutral, high-energy, reactive intermediates-fleeting chemical entities that undergo rapid reactions. An alkyne (R3C≡CR4) is a fundamental functional group that houses a high degree of potential energy; however, the substantial kinetic stability of alkynes renders them conveniently handleable as shelf-stable chemical commodities. The ability to generate metal-free carbenes directly from alkynes, fuelled by the high potential (that is, thermodynamic) energy of the latter, would constitute a considerable advance. We report here that this can be achieved simply by warming a mixture of a 2-alkynyl iminoheterocycle (a cyclic compound containing a nucleophilic nitrogen atom) with an electrophilic alkyne. We demonstrate considerable generality for the process: many shelf-stable alkyne electrophiles engage many classes of (2-alkynyl)heterocyclic nucleophiles to produce carbene intermediates that immediately undergo many types of transformations to provide facile and practical access to a diverse array of heterocyclic products. Key mechanistic aspects of the reactions are delineated.
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Affiliation(s)
- Qian Xu
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA.
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3
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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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4
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Xu Q, Hoye TR. A Cascade of Strain-Driven Events Converting Benzynes to Alkynylbenzocyclobutenes to 1,3-Dien-5-ynes to Cyclic Allenes to Benzocyclohexadienones. J Am Chem Soc 2024; 146:6438-6443. [PMID: 38437506 DOI: 10.1021/jacs.3c10225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Abstract
Here, we report a strain-promoted cascade reaction that proceeds via multiple strained intermediates, ultimately driven by the high potential energy inherent in alkyne triple bonds (C≡C). More specifically, four alkynes (three from an HDDA benzyne precursor and the fourth from a conjugated enyne reaction partner) are transformed into eight of the skeletal carbons in the benzocyclohexadienone products. The reaction pathway proceeds sequentially via strained benzyne, benzocyclobutene, and cyclic allene intermediates. DFT computations suggest that the slowest step following benzyne generation is the 4π-electrocyclic ring-opening of the alkynylbenzocyclobutene to a 1,3-dien-5-yne (an alkynylxylylene) intermediate. The activation energy for the subsequent 6π-electrocyclic ring-closure is lower than that for related acyclic dienynes because of the aromaticity that is being regained in the transition structure. Finally, the isolation of the benzocyclohexadienone products rather than their phenolic tautomers is notable.
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Affiliation(s)
- Qian Xu
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
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5
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Zhao C, Bhagwandin DD, Xu W, Ruffieux P, Khan SI, Pignedoli CA, Fasel R, Rubin Y. Dramatic Acceleration of the Hopf Cyclization on Gold(111): From Enediynes to Peri-Fused Diindenochrysene Graphene Nanoribbons. J Am Chem Soc 2024; 146:2474-2483. [PMID: 38227949 PMCID: PMC10835731 DOI: 10.1021/jacs.3c10144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
Hopf et al. reported the high-temperature 6π-electrocyclization of cis-hexa-1,3-diene-5-yne to benzene in 1969. Subsequent studies using this cyclization have been limited by its very high reaction barrier. Here, we show that the reaction barrier for two model systems, (E)-1,3,4,6-tetraphenyl-3-hexene-1,5-diyne (1a) and (E)-3,4-bis(4-iodophenyl)-1,6-diphenyl-3-hexene-1,5-diyne (1b), is decreased by nearly half on a Au(111) surface. We have used scanning tunneling microscopy (STM) and noncontact atomic force microscopy (nc-AFM) to monitor the Hopf cyclization of enediynes 1a,b on Au(111). Enediyne 1a undergoes two sequential, quantitative Hopf cyclizations, first to naphthalene derivative 2, and finally to chrysene 3. Density functional theory (DFT) calculations reveal that a gold atom from the Au(111) surface is involved in all steps of this reaction and that it is crucial to lowering the reaction barrier. Our findings have important implications for the synthesis of novel graphene nanoribbons. Ullmann-like coupling of enediyne 1b at 20 °C on Au(111), followed by a series of Hopf cyclizations and aromatization reactions at higher temperatures, produces nanoribbons 12 and 13. These results show for the first time that graphene nanoribbons can be synthesized on a Au(111) surface using the Hopf cyclization mechanism.
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Affiliation(s)
- Chenxiao Zhao
- Nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Dayanni D Bhagwandin
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles Young Dr. East, Los Angeles, California 90095-1567, United States
| | - Wangwei Xu
- Nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Pascal Ruffieux
- Nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Saeed I Khan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles Young Dr. East, Los Angeles, California 90095-1567, United States
| | - Carlo A Pignedoli
- Nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Roman Fasel
- Nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Yves Rubin
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles Young Dr. East, Los Angeles, California 90095-1567, United States
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6
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Jiang L, Peng Z, Liang Y, Tang ZB, Liang K, Liu J, Liu Z. Strain-Driven Formal [1,3]-Aryl Shift within Molecular Bows. Angew Chem Int Ed Engl 2023; 62:e202312238. [PMID: 37656430 DOI: 10.1002/anie.202312238] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 09/01/2023] [Accepted: 09/01/2023] [Indexed: 09/02/2023]
Abstract
Delving into the influence of strain on organic reactions in small molecules at the molecular level can unveil valuable insight into developing innovative synthetic strategies and structuring molecules with superior properties. Herein, we present a molecular-strain engineering approach to facilitate the consecutive [1,2]-aryl shift (formal [1,3]-aryl shift) in molecular bows (MBs) that integrate 1,4-dimethoxy-2,5-cyclohexadiene moieties. By introducing ring strain into MBs through tethering the bow limb, we can harness the intrinsic mechanical forces to drive multistep aryl shifts from the para- to the meta- to the ortho-position. Through the use of precise intramolecular strain, the seemingly impractical [1,3]-aryl shift was realized, resulting in the formation of ortho-disubstituted products. The solvent and temperature play a crucial role in the occurrence of the [1,3]-aryl shift. The free energy calculations with inclusion of solvation support a feasible mechanism, which entails multistep carbocation rearrangements, for the formal [1,3]-aryl shift. By exploring the application of molecular strain in synthetic chemistry, this research offers a promising direction for developing new tools and strategies towards precision organic synthesis.
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Affiliation(s)
- Liang Jiang
- Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
| | - Zhen Peng
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
| | - Yimin Liang
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
| | - Zheng-Bin Tang
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
| | - Kejiang Liang
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
| | - Jiali Liu
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
| | - Zhichang Liu
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
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7
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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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