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Faghtmann J, Eugui M, Nygaard Lamhauge J, Sofie Pladsbjerg Andresen S, Rask Østergaard A, Bjerregaard Svenningsen E, B Poulsen T, Anker Jørgensen K. An Enantioselective Aminocatalytic Cascade Reaction Affording Bioactive Hexahydroazulene Scaffolds. Chemistry 2024:e202401156. [PMID: 38564298 DOI: 10.1002/chem.202401156] [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: 03/24/2024] [Revised: 03/29/2024] [Accepted: 04/02/2024] [Indexed: 04/04/2024]
Abstract
A novel cascade reaction initiated by an enantioselective aminocatalysed 1,3-dipolar [6+4] cycloaddition between catalytically generated trienamines and 3-oxidopyridinium betaines is presented. The [6+4] cycloadduct spontaneously undergoes an intramolecular enamine-mediated aldol, hydrolysis, and E1cb sequence, which ultimately affords a chiral hexahydroazulene framework. In this process, three new C-C bonds and three new stereocenters are formed, enabled by a formal unfolding of the pyridine moiety from the dipolar reagent. The hexahydroazulenes are formed with excellent diastereo-, regio- and periselectivity (>20 : 1), up to 96 % ee, and yields up to 52 %. Synthetic elaborations of this scaffold were performed, providing access to a variety of functionalised hydroazulene compounds, of which some were found to display biological activity in U-2OS osteosarcoma cells in cell painting assays.
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Affiliation(s)
- Jonas Faghtmann
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Macarena Eugui
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | | | | | - Anne Rask Østergaard
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | | | - Thomas B Poulsen
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Karl Anker Jørgensen
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
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Lamhauge JN, McLeod DA, Barløse CL, Oliver GA, Viborg L, Warburg T, Anker Jørgensen K. Enantioselective Synthesis of Tropane Scaffolds by an Organocatalyzed 1,3-Dipolar Cycloaddition of 3-Oxidopyridinium Betaines and Dienamines. Chemistry 2023; 29:e202301830. [PMID: 37318111 DOI: 10.1002/chem.202301830] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 06/15/2023] [Accepted: 06/15/2023] [Indexed: 06/16/2023]
Abstract
Tropane alkaloids constitute a compound-class which is structurally defined by a central 8-azabicyclo[3.2.1]octane core. A diverse bioactivity profile combined with an unusual aza-bridged bicyclic framework has made tropanes molecules-of-interest within organic chemistry. Enantioselective examples of (5+2) cycloadditions between 3-oxidopyridinium betaines and olefins remain unexplored, despite 3-oxidopyridinium betaines being useful reagents in organic synthesis. The first asymmetric (5+2) cycloaddition of 3-oxidopyridinium betaines is reported, affording tropane derivatives in up to quantitative yield and with excellent control of peri-, regio-, diastereo-, and enantioselectivity. The reactivity is enabled by dienamine-activation of α,β-unsaturated aldehydes combined with in situ formation of the pyridinium reaction-partner. A simple N-deprotection protocol allows for liberation of the tropane alkaloid motif, and synthetic elaborations of the cycloadducts demonstrate their synthetic utility to achieve highly diastereoselective modification around the bicyclic framework. DFT computations suggest a stepwise mechanism where regio- and stereoselectivity are defined during the first bond-forming step in which the pyridinium dipole exerts critical conformational control over its dienamine partner. In the second bond-forming step, a kinetic preference toward an initial (5+4) cycloadduct was identified; however, a lack of catalyst turn-over, reversibility, and thermodynamic bias favoring a (5+2) cycloadduct rendered the reaction fully periselective.
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Affiliation(s)
- Johannes N Lamhauge
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - David A McLeod
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Casper L Barløse
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Gwyndaf A Oliver
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Laura Viborg
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Tobias Warburg
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Karl Anker Jørgensen
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
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Shen L, Zheng Y, Lin Z, Qin T, Huang Z, Zi W. Copper-Catalyzed Enantioselective C1,N-Dipolar (3+2) Cycloadditions of 2-Aminoallyl Cations with Indoles. Angew Chem Int Ed Engl 2023; 62:e202217051. [PMID: 36562702 DOI: 10.1002/anie.202217051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 12/21/2022] [Accepted: 12/23/2022] [Indexed: 12/24/2022]
Abstract
2-Aminoallyl cations are versatile 1,3-dipoles that could potentially be used for diverse (3+n) cycloaddition reactions. Despite some preliminary studies, the asymmetric catalytic transformation of these species is still underdeveloped. We herein report a binuclear copper-catalyzed generation of 2-aminoallyl cations from ethynyl methylene cyclic carbamates and their enantioselective (3+2) cycloaddition reaction with indoles to construct chiral pyrroloindolines. This transformation features a novel C1,N-dipolar reactivity for 2-aminoallyl cations.
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Affiliation(s)
- Lulu Shen
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, P. R. China
| | - Yin Zheng
- State Key Laboratory of Synthetic Chemistry, Department of Chemistry, University of Hong Kong, Hong Kong, P. R. China
| | - Zitong Lin
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, P. R. China
| | - Tianzhu Qin
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, P. R. China
| | - Zhongxing Huang
- State Key Laboratory of Synthetic Chemistry, Department of Chemistry, University of Hong Kong, Hong Kong, P. R. China
| | - Weiwei Zi
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, P. R. China.,Haihe Laboratory of Sustainable Chemical Transformations, Tianjin, 300071, China
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Huang J, Jiang B, Zhang X, Gao Y, Xu X, Miao Z. Triethyamine‐promoted [5+3] Cycloadditions for Regio‐ and Diastereoselective Synthesis of Functionalized aza‐Bicyclo[3.3.1]alkenones. Adv Synth Catal 2022. [DOI: 10.1002/adsc.202200764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | | | | | | | | | - Zhiwei Miao
- Institute of Elemento-Organic Chemistry CHINA
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Tu J, Ripa RA, Kelley SP, Harmata M. Intramolecular (4+3) Cycloadditions of Oxidopyridinium Ions: Towards Daphnicyclidin A. Chemistry 2022; 28:e202200370. [PMID: 35612968 DOI: 10.1002/chem.202200370] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Indexed: 12/15/2022]
Abstract
N-alkylation of 5-hydroxynicotinic acid esters with electrophiles containing diene functionality produces salts that undergo intramolecular (4+3) cycloaddition reactions upon heating in the presence of base. Initial studies used a three-carbon tether to join the pyridinium ion and diene, revealing some aspects of the inherent selectivity of the reaction with such substrates. Much more challenging was the synthesis of related species possessing only a two-carbon tether. Nevertheless, the cycloaddition of such compounds was successful, leading directly to the ABC ring system of the alkaloid daphnicyclidin A.
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Affiliation(s)
- Jianzhuo Tu
- Department of Chemistry, University of Missouri-Columbia, 601 S. College Avenue, Columbia, Missouri, 65211, USA
| | - Rawshan A Ripa
- Department of Chemistry, University of Missouri-Columbia, 601 S. College Avenue, Columbia, Missouri, 65211, USA
| | - Steven P Kelley
- Department of Chemistry, University of Missouri-Columbia, 601 S. College Avenue, Columbia, Missouri, 65211, USA
| | - Michael Harmata
- Department of Chemistry, University of Missouri-Columbia, 601 S. College Avenue, Columbia, Missouri, 65211, USA
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