1
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Blank L, Kim J, Daniliuc CG, Goetzinger A, Müller MA, Schütz J, Wuestenberg B, Gilmour R. Deconjugative Photoisomerization of Cyclic Enones. J Am Chem Soc 2025; 147:10023-10030. [PMID: 40053914 DOI: 10.1021/jacs.5c01814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2025]
Abstract
The deconjugative isomerization of α,β-unsaturated carbonyl compounds enables regioisomeric products to be forged with simultaneous Umpolung of alkene reactivity. Although highly enabling, the endergonic nature of the net process coupled with governing regioselectivity outcomes, renders it challenging. Innovations in the positional isomerization of linear species, often by light-triggered activation, have re-energized this area. However, the deconjugative isomerization of cyclic enones is underdeveloped and often associated with impractical reaction conditions, limited substrate scopes, and a lack of mechanistic clarity. Herein, we report an operationally simple photochemical isomerization of cyclic enones using near-UV (372 nm) irradiation with catalytic amounts of Brønsted acid (HCl). This platform enables exocyclic deconjugative isomerization of a diverse array of enones including α-isophorone (a key intermediate in a variety of industrial processes), terpenoids and steroids. Mechanistic studies reveal the pivotal role of the solvent as a key mediator in the isomerization, where sequential hydrogen atom transfer (HAT) and reverse-HAT (RHAT) are proposed to be operational.
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Affiliation(s)
- Lukas Blank
- Institute for Organic Chemistry, University of Münster, Corrensstraβe 36, Münster 48149, Germany
| | - Jungwon Kim
- Department of Chemistry, Gyeongsang National University, 501, Jinju 52828, Republic of Korea
| | - Constantin G Daniliuc
- Institute for Organic Chemistry, University of Münster, Corrensstraβe 36, Münster 48149, Germany
| | | | | | - Jan Schütz
- DSM-Firmenich AG, Wurmisweg 576, Kaiseraugst 4303, Switzerland
| | | | - Ryan Gilmour
- Institute for Organic Chemistry, University of Münster, Corrensstraβe 36, Münster 48149, Germany
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2
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Thompson J, Le NH, Pluemer J, Chen R, Dooley CJ, Ziller JW, Rychnovsky SD. Cyclic Osmate Esters from 1,2- and 1,3-Diols and α-Hydroxy Acids for X-ray Analysis. J Org Chem 2025; 90:2493-2499. [PMID: 39908581 PMCID: PMC11833874 DOI: 10.1021/acs.joc.4c03119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2024] [Revised: 01/16/2025] [Accepted: 01/27/2025] [Indexed: 02/07/2025]
Abstract
We previously demonstrated that osmium tetroxide and TMEDA generate stable crystalline adducts with alkenes that facilitate X-ray analysis and structure assignments. Alternatively, osmate esters can be prepared from diols, potassium osmate, and TMEDA·2TsOH in a nonoxidative condensation reaction. This new approach provides a convenient route to form stable, crystalline osmate(VI) esters for X-ray analysis. Because it is redox neutral, it works with a variety of diol substrates, including 1,3-diols, that cannot be prepared from alkenes. α-Hydroxy acids also form stable osmate esters in reasonable yields and readily crystallize. An alternative ligand screen was performed to assess the improved crystallinity from substituted TMEDA analogues. The enhanced crystallinity of osmate esters and the incorporation of a heavy atom make a reliable determination of structure and absolute configuration routine.
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Affiliation(s)
- Jordan
C. Thompson
- Department of Chemistry, University of California at Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Ngoc H. Le
- Department of Chemistry, University of California at Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Jace Pluemer
- Department of Chemistry, University of California at Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Ruby Chen
- Department of Chemistry, University of California at Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | | | - Joseph W. Ziller
- Department of Chemistry, University of California at Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Scott D. Rychnovsky
- Department of Chemistry, University of California at Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
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3
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Summersgill MD, Gahan LR, Chow S, Pierens GK, Bernhardt PV, Krenske EH, Williams CM. Hyperstable alkenes: are they remarkably unreactive? Chem Sci 2024; 15:19299-19306. [PMID: 39568885 PMCID: PMC11575626 DOI: 10.1039/d4sc06697a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2024] [Accepted: 10/21/2024] [Indexed: 11/22/2024] Open
Abstract
In 1981, Maier and Schleyer first identified a select number of cage bicyclic olefins (alkenes) as "hyperstable", and predicted them to be "remarkably unreactive", based solely on theoretical methods. Since that time only three ad hoc systems meeting the criteria of a hyperstable alkene have been reported in the literature. A one-pot, telescoped synthesis, of four hyperstable alkenes is reported herein, which has uncovered unexpected reactivity towards oxidation. Although, this work represents a new benchmark in hyperstable alkenes, it concomitantly emphasised the need to clarify the definition based on a long-held computational prediction.
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Affiliation(s)
- Matthew D Summersgill
- School of Chemistry and Molecular Biosciences, University of Queensland Brisbane 4072 Queensland Australia
| | - Lawrence R Gahan
- School of Chemistry and Molecular Biosciences, University of Queensland Brisbane 4072 Queensland Australia
| | - Sharon Chow
- School of Chemistry and Molecular Biosciences, University of Queensland Brisbane 4072 Queensland Australia
| | - Gregory K Pierens
- Centre for Advanced Imaging, University of Queensland Brisbane 4072 Queensland Australia
| | - Paul V Bernhardt
- School of Chemistry and Molecular Biosciences, University of Queensland Brisbane 4072 Queensland Australia
| | - Elizabeth H Krenske
- School of Chemistry and Molecular Biosciences, University of Queensland Brisbane 4072 Queensland Australia
| | - Craig M Williams
- School of Chemistry and Molecular Biosciences, University of Queensland Brisbane 4072 Queensland Australia
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Chinta BS, Sneddon DS, Hoye TR. Cascade reactions of HDDA-benzynes with tethered cyclohexadienones: strain-driven events originating from ortho-annulated benzocyclobutenes. Chem Sci 2024; 15:8181-8189. [PMID: 38817592 PMCID: PMC11134320 DOI: 10.1039/d4sc00571f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 04/16/2024] [Indexed: 06/01/2024] Open
Abstract
Intramolecular net [2 + 2] cycloadditions between benzyne intermediates and an electron-deficient alkene to give benzocyclobutene intermediates are relatively rare. Benzynes are electrophilic and generally engage nucleophiles or electron-rich π-systems. We describe here reactions in which an alkene of a tethered enone traps thermally generated benzynes in a variety of interesting ways. The number of atoms that link the benzyne to C4 of a cyclohexa-2,5-dienone induces varying amounts of strain in the intermediates and products. This leads to a variety of different reaction outcomes by way of various strain-releasing events that are mechanistically intriguing. This work demonstrates an underappreciated class of strain that originates from the adjacent fusion of two rings to both C1-C2 and C2-C3 of a benzenoid ring - i.e. 'ortho-annulation strain'. DFT computations shed considerable light on the mechanistic diversions among various reaction pathways as well as allow more fundamental evaluation of the strain in a homologous series of ortho-annulated carbocycles.
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Affiliation(s)
- Bhavani Shankar Chinta
- 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
| | - Thomas R Hoye
- Department of Chemistry, University of Minnesota 207 Pleasant St. SE Minneapolis MN 55455 USA
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Wakchaure VN, DeSnoo W, Laconsay CJ, Leutzsch M, Tsuji N, Tantillo DJ, List B. Catalytic asymmetric cationic shifts of aliphatic hydrocarbons. Nature 2024; 625:287-292. [PMID: 38200298 PMCID: PMC10781632 DOI: 10.1038/s41586-023-06826-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 11/02/2023] [Indexed: 01/12/2024]
Abstract
Asymmetric catalysis is an advanced area of chemical synthesis, but the handling of abundantly available, purely aliphatic hydrocarbons has proven to be challenging. Typically, heteroatoms or aromatic substructures are required in the substrates and reagents to facilitate an efficient interaction with the chiral catalyst. Confined acids have recently been introduced as tools for homogenous asymmetric catalysis, specifically to enable the processing of small unbiased substrates1. However, asymmetric reactions in which both substrate and product are purely aliphatic hydrocarbons have not previously been catalysed by such super strong and confined acids. We describe here an imidodiphosphorimidate-catalysed asymmetric Wagner-Meerwein shift of aliphatic alkenyl cycloalkanes to cycloalkenes with excellent regio- and enantioselectivity. Despite their long history and high relevance for chemical synthesis and biosynthesis, Wagner-Meerwein reactions utilizing purely aliphatic hydrocarbons, such as those originally reported by Wagner and Meerwein, had previously eluded asymmetric catalysis.
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Affiliation(s)
- Vijay N Wakchaure
- Max Planck Institut für Kohlenforschung, Mülheim an der Ruhr, Germany
| | - William DeSnoo
- Department of Chemistry, University of California, Davis, Davis, CA, USA
| | - Croix J Laconsay
- Department of Chemistry, University of California, Davis, Davis, CA, USA
| | - Markus Leutzsch
- Max Planck Institut für Kohlenforschung, Mülheim an der Ruhr, Germany
| | - Nobuya Tsuji
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Japan
| | - Dean J Tantillo
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - Benjamin List
- Max Planck Institut für Kohlenforschung, Mülheim an der Ruhr, Germany.
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Japan.
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Davies TQ, Kim JY, Fürstner A. Nickel-Catalyzed Enantioselective Coupling of Aldehydes and Electron-Deficient 1,3-Dienes Following an Inverse Regiochemical Course. J Am Chem Soc 2022; 144:18817-18822. [PMID: 36194199 PMCID: PMC9585590 DOI: 10.1021/jacs.2c09328] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The nickel catalyzed reductive coupling of aldehydes with sorbate esters and related electron-deficient 1,3-dienes are known in the literature to occur at the π-bond proximal to the ester to afford aldol-type products. In stark contrast to this established path, a VAPOL-derived phosphoramidite ligand in combination with a bench-stable nickel precatalyst brokers a regiocomplementary course in that C-C bond formation proceeds exclusively at the distal alkene site to give deoxypropionate type products carrying an acrylate handle; they can be made in either anti- or syn-configured form. In addition to this enabling reverse pathway, the reaction is distinguished by excellent levels of chemo-, diastereo-, and enantioselectivity; moreover, it can be extended to the catalytic formation of F3C-substituted stereogenic centers. The use of a dienyl pinacolboronate instead of a sorbate ester is also possible, which opens access to valuable chiral borylated building blocks in optically active form.
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Affiliation(s)
- Thomas Q Davies
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany
| | - Jae Yeon Kim
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany
| | - Alois Fürstner
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany
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Huo ZQ, Zhu F, Zhang XW, Zhang X, Liang HB, Yao JC, Liu Z, Zhang GM, Yao QQ, Qin GF. Approaches to Configuration Determinations of Flexible Marine Natural Products: Advances and Prospects. Mar Drugs 2022; 20:333. [PMID: 35621984 PMCID: PMC9143581 DOI: 10.3390/md20050333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/16/2022] [Accepted: 05/17/2022] [Indexed: 02/07/2023] Open
Abstract
Flexible marine natural products (MNPs), such as eribulin and bryostatin, play an important role in the development of modern marine drugs. However, due to the multiple chiral centers and geometrical uncertainty of flexible systems, configuration determinations of flexible MNPs face great challenges, which, in turn, have led to obstacles in druggability research. To resolve this issue, the comprehensive use of multiple methods is necessary. Additionally, configuration assignment methods, such as X-ray single-crystal diffraction (crystalline derivatives, crystallization chaperones, and crystalline sponges), NMR-based methods (JBCA and Mosher's method), circular dichroism-based methods (ECCD and ICD), quantum computational chemistry-based methods (NMR calculations, ECD calculations, and VCD calculations), and chemical transformation-based methods should be summarized. This paper reviews the basic principles, characteristics, and applicability of the methods mentioned above as well as application examples to broaden the research and applications of these methods and to provide a reference for the configuration determinations of flexible MNPs.
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Affiliation(s)
- Zong-Qing Huo
- State Key Laboratory of Generic Manufacture Technology of Chinese Traditional Medicine, Lunan Pharmaceutical Group Co., Ltd., Linyi 273400, China; (Z.-Q.H.); (F.Z.); (H.-B.L.); (J.-C.Y.); (Z.L.); (G.-M.Z.)
| | - Feng Zhu
- State Key Laboratory of Generic Manufacture Technology of Chinese Traditional Medicine, Lunan Pharmaceutical Group Co., Ltd., Linyi 273400, China; (Z.-Q.H.); (F.Z.); (H.-B.L.); (J.-C.Y.); (Z.L.); (G.-M.Z.)
| | - Xing-Wang Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Xiao Zhang
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China;
| | - Hong-Bao Liang
- State Key Laboratory of Generic Manufacture Technology of Chinese Traditional Medicine, Lunan Pharmaceutical Group Co., Ltd., Linyi 273400, China; (Z.-Q.H.); (F.Z.); (H.-B.L.); (J.-C.Y.); (Z.L.); (G.-M.Z.)
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China;
| | - Jing-Chun Yao
- State Key Laboratory of Generic Manufacture Technology of Chinese Traditional Medicine, Lunan Pharmaceutical Group Co., Ltd., Linyi 273400, China; (Z.-Q.H.); (F.Z.); (H.-B.L.); (J.-C.Y.); (Z.L.); (G.-M.Z.)
| | - Zhong Liu
- State Key Laboratory of Generic Manufacture Technology of Chinese Traditional Medicine, Lunan Pharmaceutical Group Co., Ltd., Linyi 273400, China; (Z.-Q.H.); (F.Z.); (H.-B.L.); (J.-C.Y.); (Z.L.); (G.-M.Z.)
| | - Gui-Min Zhang
- State Key Laboratory of Generic Manufacture Technology of Chinese Traditional Medicine, Lunan Pharmaceutical Group Co., Ltd., Linyi 273400, China; (Z.-Q.H.); (F.Z.); (H.-B.L.); (J.-C.Y.); (Z.L.); (G.-M.Z.)
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, China;
| | - Qing-Qiang Yao
- Institute of Materia Medica, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan 250000, China;
| | - Guo-Fei Qin
- State Key Laboratory of Generic Manufacture Technology of Chinese Traditional Medicine, Lunan Pharmaceutical Group Co., Ltd., Linyi 273400, China; (Z.-Q.H.); (F.Z.); (H.-B.L.); (J.-C.Y.); (Z.L.); (G.-M.Z.)
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8
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Carlson PR, Burns AS, Shimizu EA, Wang S, Rychnovsky SD. Silacycle-Templated Intramolecular Diels-Alder Cyclizations for the Diastereoselective Construction of Complex Carbon Skeletons. Org Lett 2021; 23:2183-2188. [PMID: 33635083 DOI: 10.1021/acs.orglett.1c00340] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The utility of the dioxasiline ring as a π-facial directing group in the intramolecular Diels-Alder cyclization is explored. An initial investigation of substrate scope demonstrates that the rigidity of this directing group delivers robust stereocontrol across a number of substrates, affording single diastereomers in moderate to good yields. A mechanistic investigation reveals that the reactive diene is formed through γ deprotonation followed by [1,5] hydride shifts.
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Affiliation(s)
- Paul R Carlson
- Department of Chemistry, University of California at Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Alexander S Burns
- Department of Chemistry, University of California at Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Emily A Shimizu
- Department of Chemistry, University of California at Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Shilin Wang
- Department of Chemistry, University of California at Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Scott D Rychnovsky
- Department of Chemistry, University of California at Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
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Smith KL, Padgett CL, Mackay WD, Johnson JS. Catalytic, Asymmetric Dearomative Synthesis of Complex Cyclohexanes via a Highly Regio- and Stereoselective Arene Cyclopropanation Using α-Cyanodiazoacetates. J Am Chem Soc 2020; 142:6449-6455. [PMID: 32227868 DOI: 10.1021/jacs.9b13080] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Arene cyclopropanation offers a direct route to higher-order, non-aromatic carbocycles; however, the inherent issue of dictating site selectivity has cumbered the development of novel intermolecular reactions that directly engage the arene pool. This paper describes a highly regio- and stereoselective, Rh2[(S)-PTTL]4-catalyzed arene cyclopropanation using α-cyanodiazoacetates to afford stable norcaradienes bearing three stereogenic centers, one of which is an all-carbon quaternary center. The enantioenriched norcaradienes served as tunable templates for further transformation into stereochemically dense, fused and bicyclic carbocycles containing transmutable functionality.
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Affiliation(s)
- Kendrick L Smith
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Cody L Padgett
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - William D Mackay
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Jeffrey S Johnson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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