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Sanchez A, Gonzalez VM, Sakamoto J, Gurajapu A, Maimone TJ. Modular, Enantioselective Entry into Polysubstituted Shapeshifting Molecules. J Am Chem Soc 2024; 146:17573-17579. [PMID: 38901002 DOI: 10.1021/jacs.4c03323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
Dynamic, shapeshifting hydrocarbons have emerged as enabling frameworks across drug discovery, materials science, and catalysis. Their employment, however, is often hampered by a lack of efficient synthetic methods for their preparation. Herein, we report a unified, concise, and modular synthesis of enantioenriched shapeshifting hydrocarbons (barbaralones and bullvalones) and multisubstituted bullvalenes, leveraging mild photochemical and base-induced rearrangements.
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Affiliation(s)
- Andre Sanchez
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California, 94720, United States
| | - Vanessa M Gonzalez
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California, 94720, United States
| | - Jukiya Sakamoto
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California, 94720, United States
| | - Anjali Gurajapu
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California, 94720, United States
| | - Thomas J Maimone
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California, 94720, United States
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Dohmen C, Paululat T, Ihmels H. Reversible Restrain and Release of the Dynamic Valence Isomerization in a Shape-shifting Bullvalene by Complex Formation. Chemistry 2024; 30:e202304311. [PMID: 38275100 DOI: 10.1002/chem.202304311] [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: 12/24/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 01/27/2024]
Abstract
In search for structural features that enable the control of the valence isomerization of the fluxional bullvalene, a bullvalene-bis(harmane) conjugate is identified that acts as chelating ligand in complexes with metal ions. Spectrometric titrations show that this ligand forms 1 : 1 complexes with Ag+, Cu+, Cu2+, and Zn2+. Most importantly, detailed NMR-spectroscopic analysis at different temperatures reveals that the complexation with Ag+ strongly affects the dynamic isomerization of the bullvalene unit of the ligand such that only one predominant valence isomer is formed, even at 5 °C. Detailed 1H-NMR-spectroscopic studies disclose an increased barrier (~11 kJ mol-1) of the Cope rearrangement. Furthermore, the addition of hexacyclene displaces the Ag+ from the complex, so that the valence isomerization is accelerated and an equilibrium with two predominant isomers is formed. In turn, repeated addition of Ag+ regains the complex with the restrained isomerization of the bullvalene unit. This method to control the valence isomerism by straightforward chemical stimuli may be used to simplify structural analysis at elevated temperatures, i. e. a feature not available so far with bullvalenes, and it may be employed as functional element in dynamic supramolecular assemblies.
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Affiliation(s)
- Christoph Dohmen
- Department of Chemistry-Biology, and Center of Micro-and Nanochemistry and (Bio)Technology (Cμ), University of Siegen, Adolf-Reichwein-Str. 2, 57068, Siegen, Germany
| | - Thomas Paululat
- Department of Chemistry-Biology, and Center of Micro-and Nanochemistry and (Bio)Technology (Cμ), University of Siegen, Adolf-Reichwein-Str. 2, 57068, Siegen, Germany
| | - Heiko Ihmels
- Department of Chemistry-Biology, and Center of Micro-and Nanochemistry and (Bio)Technology (Cμ), University of Siegen, Adolf-Reichwein-Str. 2, 57068, Siegen, Germany
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3
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Bismillah AN, Johnson TG, Hussein BA, Turley AT, Saha PK, Wong HC, Aguilar JA, Yufit DS, McGonigal PR. Control of dynamic sp 3-C stereochemistry. Nat Chem 2023; 15:615-624. [PMID: 36914791 PMCID: PMC10159849 DOI: 10.1038/s41557-023-01156-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 02/09/2023] [Indexed: 03/16/2023]
Abstract
Stereogenic sp3-hybridized carbon centres are fundamental building blocks of chiral molecules. Unlike dynamic stereogenic motifs, such as sp3-nitrogen centres or atropisomeric biaryls, sp3-carbon centres are usually fixed, requiring intermolecular reactions to undergo configurational changes. Here we report the internal enantiomerization of fluxional carbon cages and the consequences of their adaptive configurations for the transmission of stereochemical information. The sp3-carbon stereochemistry of the rigid tricyclic cages is inverted through strain-assisted Cope rearrangements, emulating the low-barrier configurational dynamics typical for sp3-nitrogen inversion or conformational isomerism. This dynamic enantiomerization can be stopped, restarted or slowed by external reagents, while the configuration of the cage is controlled by neighbouring, fixed stereogenic centres. As part of a phosphoramidite-olefin ligand, the fluxional cage acts as a conduit to transmit stereochemical information from the ligand while also transferring its dynamic properties to chiral-at-metal coordination environments, influencing catalysis, ion pairing and ligand exchange energetics.
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Affiliation(s)
| | | | | | | | | | - Ho Chi Wong
- Department of Chemistry, Durham University, Durham, UK
| | | | | | - Paul R McGonigal
- Department of Chemistry, Durham University, Durham, UK. .,Department of Chemistry, University of York, York, UK.
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4
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Sanchez A, Maimone TJ. Taming Shapeshifting Anions: Total Synthesis of Ocellatusone C. J Am Chem Soc 2022; 144:7594-7599. [PMID: 35420799 DOI: 10.1021/jacs.2c02627] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Guided by a synthetic design aimed at late-stage diversification, we report the preparation of unusual shapeshifting anions and their subsequent application to the total synthesis of the polyketide natural product ocellatusone C. Site-selective core functionalization of a readily accessible bicyclo[3.3.1]nonane architecture sets the stage for shape-selective side chain installation via a nonfluxional π-allyl Pd-complex derived from a barbaralyl-type anion. Several interesting chemical findings, including substituent-dependent bridged bicycloisomerism and the isolation of a stabilized, 3° carbon-bound Pd-ketone enolate complex, are reported.
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Affiliation(s)
- Andre Sanchez
- Department of Chemistry, University of California─Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
| | - Thomas J Maimone
- Department of Chemistry, University of California─Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
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5
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Birvé AP, Patel HD, Price JR, Bloch WM, Fallon T. Guest‐Dependent Isomer Convergence of a Permanently Fluxional Coordination Cage. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- André P. Birvé
- Department of Chemistry University of Adelaide Adelaide 5005 Australia
| | - Harshal D. Patel
- Department of Chemistry University of Adelaide Adelaide 5005 Australia
| | - Jason R. Price
- ANSTO Australian Synchrotron 800 Blackburn Road Clayton Vic 3168 Australia
| | - Witold M. Bloch
- Department of Chemistry University of Adelaide Adelaide 5005 Australia
| | - Thomas Fallon
- Department of Chemistry University of Adelaide Adelaide 5005 Australia
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6
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Patel HD, Gaggl S, Pašteka LF, Fallon T. Ambimodal Pericyclic Rearrangements of Dialkenyl-Bullvalenes Give Tetrahydro-1,8-ethenoheptalenes. Org Lett 2021; 24:319-323. [PMID: 34898219 DOI: 10.1021/acs.orglett.1c03984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fluxional structure of bullvalene is expanded by the discovery of a [5,5]-sigmatropic rearrangement of dialkenyl substituted derivatives. This gives rise to tetrahydro-1,8-ethenoheptalenes (THEH), representing the first examples of this tricyclic scaffold. Variation of the substitution pattern alters the product distribution, including one thermodynamically balanced between THEH and bullvalene isomers. DFT calculations are used to explore the thermodynamic landscape and reaction mechanism revealing a pretransition state bifurcation leading to a concerted ambimodal rearrangement pathway.
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Affiliation(s)
- Harshal D Patel
- Department of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Sebastian Gaggl
- Department of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Lukáš F Pašteka
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, 842 15 Bratislava, Slovakia
| | - Thomas Fallon
- Department of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
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Fallon T, Birve A, Patel HD, Price JR, Bloch WM. Guest-Dependent Isomer Convergence of a Permanently Fluxional Coordination Cage. Angew Chem Int Ed Engl 2021; 61:e202115468. [PMID: 34854191 PMCID: PMC9303423 DOI: 10.1002/anie.202115468] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Indexed: 11/09/2022]
Abstract
A fluxional bis-monodentate ligand, based on the archetypal shape-shifting molecule bullvalene, self-assembles with M2+ (M = Pd2+ or Pt2+) to produce a highly complex ensemble of permanently fluxional coordination cages. Metal-mediated self-assembly selects for an M2L4 architecture while maintaining shape-shifting ligand complexity. A second level of simplification is achieved with guest-exchange; the binding of halides within the M2L4 cage mixture results in a convergence to a cage species with all four ligands present as the "B isomer". Within this confine, the reaction graph of the bullvalene is greatly restricted, but gives rise to a mixture of 38 possible diastereoisomers in rapid exchange. X-ray crystallography reveals a preference for an achiral form consisting of both ligand enantiomers. Through a combination of NMR spectroscopy and DFT calculations, we elucidate the restricted isomerisation pathway of the permanently fluxional M2L4 assembly.
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Affiliation(s)
- Thomas Fallon
- The University of Adelaide Adelaide Medical School, Department of Chemistry, Badger Laboratories, North Terrace, Adelaide, 5000, Adelaide, AUSTRALIA
| | - Andre Birve
- The University of Adelaide, Department of Chemistry, AUSTRALIA
| | | | - Jason R Price
- Australian Nuclear Science and Technology Organisation, Australian Synchrotron, AUSTRALIA
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