1
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Johny M, Rajendar G. Effective In Situ Alkoxide Trapping by TMSX in the Presence of TPP Catalyst in Glycidol Acetal Rearrangements. J Org Chem 2024; 89:7036-7046. [PMID: 38716502 DOI: 10.1021/acs.joc.4c00408] [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
This study demonstrates a nucleophile-catalyzed, trimethylsilyl halide-promoted rearrangement reaction of glycidol acetals to form halogenated cyclic acetals. The acetal group has been activated selectively in the presence of trimethylsilyl cation, which is used as in situ-generated alkoxide trapping reagent. Nucleophilic chloride and bromide ions participate in addition reactions with epoxides predominantly via SN1-type epoxide opening, while non-nucleophilic iodide and triflate ions induce a positive charge at the epoxide carbon. A systematic investigation of acetal-initiated polyene cyclization of epoxy polyenes has been conducted using bicyclic epoxonium ions as transient intermediates. Unfavorable orbital orientation and other stereoelectronic factors hinder the much-anticipated polyene cyclizations. The potential of this method has been showcased through its application in the total synthesis of parvistone A, a chlorinated styryllactone.
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Affiliation(s)
- Meera Johny
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - Goreti Rajendar
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
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2
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Ugartemendia A, Casademont-Reig I, Zhao L, Zhang Z, Frenking G, Ugalde JM, Garcia-Lekue A, Jimenez-Izal E. Deciphering the chemical bonding of the trivalent oxygen atom in oxygen doped graphene. Chem Sci 2024; 15:6151-6159. [PMID: 38665533 PMCID: PMC11041353 DOI: 10.1039/d4sc00142g] [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: 01/08/2024] [Accepted: 03/25/2024] [Indexed: 04/28/2024] Open
Abstract
Recently, planar and neutral tricoordinated oxygen embedded in graphene has been imaged experimentally (Nat. Commun., 2019, 10, 4570-4577). In this work, this unusual chemical species is studied utilizing a variety of state-of-the-art methods and combining periodic calculations with a fragmental approach. Several factors influencing the stability of trivalent oxygen are identified. A σ-donation and a π-backdonation mechanism between graphite and oxygen is established. π-Local aromaticity, with a delocalized 4c-2e bond involving the oxygen atom and the three nearest carbon atoms aids in the stabilization of this system. In addition, the framework in which the oxygen is embedded is crucial too to the stabilization, helping to delocalize the "extra" electron pair in the virtual orbitals. Based on the understanding gathered in this work, a set of organic molecules containing planar and neutral trivalent oxygen is theoretically proposed for the first time.
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Affiliation(s)
- Andoni Ugartemendia
- Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia Saila, Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU) M. de Lardizabal Pasealekua 3, Donostia, Euskadi Spain
- Donostia International Physics Center (DIPC) Manuel de Lardizabal Pasealekua 3, Donostia, Euskadi Spain
| | - Irene Casademont-Reig
- Department of General Chemistry (ALGC), Vrije Universiteit Brussel (VUB) Pleinlaan 2 1050 Brussels Belgium
| | - Lili Zhao
- Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University Nanjing 211816 China
| | - Zuxian Zhang
- Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University Nanjing 211816 China
| | - Gernot Frenking
- Donostia International Physics Center (DIPC) Manuel de Lardizabal Pasealekua 3, Donostia, Euskadi Spain
- Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University Nanjing 211816 China
- Fachbereich Chemie, Philipps-Universität Marburg Hans-Meerwein-Strasse D-35043 Marburg Germany
| | - Jesus M Ugalde
- Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia Saila, Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU) M. de Lardizabal Pasealekua 3, Donostia, Euskadi Spain
- Donostia International Physics Center (DIPC) Manuel de Lardizabal Pasealekua 3, Donostia, Euskadi Spain
| | - Aran Garcia-Lekue
- Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University Nanjing 211816 China
- IKERBASQUE, Basque Foundation for Science Euskadi Bilbao Spain
| | - Elisa Jimenez-Izal
- Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia Saila, Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU) M. de Lardizabal Pasealekua 3, Donostia, Euskadi Spain
- Donostia International Physics Center (DIPC) Manuel de Lardizabal Pasealekua 3, Donostia, Euskadi Spain
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3
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Smith O, Popescu MV, Hindson MJ, Paton RS, Burton JW, Smith MD. Control of stereogenic oxygen in a helically chiral oxonium ion. Nature 2023; 615:430-435. [PMID: 36922609 PMCID: PMC10017494 DOI: 10.1038/s41586-023-05719-z] [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: 07/26/2022] [Accepted: 01/09/2023] [Indexed: 03/17/2023]
Abstract
The control of tetrahedral carbon stereocentres remains a focus of modern synthetic chemistry and is enabled by their configurational stability. By contrast, trisubstituted nitrogen1, phosphorus2 and sulfur compounds3 undergo pyramidal inversion, a fundamental and well-recognized stereochemical phenomenon that is widely exploited4. However, the stereochemistry of oxonium ions-compounds bearing three substituents on a positively charged oxygen atom-is poorly developed and there are few applications of oxonium ions in synthesis beyond their existence as reactive intermediates5,6. There are no examples of configurationally stable oxonium ions in which the oxygen atom is the sole stereogenic centre, probably owing to the low barrier to oxygen pyramidal inversion7 and the perception that all oxonium ions are highly reactive. Here we describe the design, synthesis and characterization of a helically chiral triaryloxonium ion in which inversion of the oxygen lone pair is prevented through geometric restriction to enable it to function as a determinant of configuration. A combined synthesis and quantum calculation approach delineates design principles that enable configurationally stable and room-temperature isolable salts to be generated. We show that the barrier to inversion is greater than 110 kJ mol-1 and outline processes for resolution. This constitutes, to our knowledge, the only example of a chiral non-racemic and configurationally stable molecule in which the oxygen atom is the sole stereogenic centre.
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Affiliation(s)
- Owen Smith
- Chemistry Research Laboratory, University of Oxford, Oxford, UK
| | - Mihai V Popescu
- Chemistry Research Laboratory, University of Oxford, Oxford, UK
- Department of Chemistry, Colorado State University, Ft. Collins, CO, USA
| | | | - Robert S Paton
- Department of Chemistry, Colorado State University, Ft. Collins, CO, USA.
| | | | - Martin D Smith
- Chemistry Research Laboratory, University of Oxford, Oxford, UK.
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4
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Hicks H, Brown DS, Sam Chan HS, Sousa BA, Christensen KE, Burton JW. Total Synthesis and Structure Confirmation of ( E) and ( Z)-Ocellenyne. Org Lett 2022; 24:9174-9178. [PMID: 36508492 PMCID: PMC9791679 DOI: 10.1021/acs.orglett.2c03524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The (E/Z)-ocellenynes are C15 dibrominated Laurencia natural products whose structures have been subject to several reassignments on the basis of extensive NMR analysis, biosynthetic postulates, and DFT calculations. Herein, we report the synthesis of both (E)- and (Z)-ocellenyne, which, in combination with single crystal X-ray diffraction studies, allows their absolute configuration to be established and defines the configuration of the syn-12,13-dibromide as being (S, S) in keeping with their proposed biogenesis from the (6S, 7S)-laurediols.
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Affiliation(s)
- Harry
B. Hicks
- Chemistry
Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, U.K.
| | - Daniel S. Brown
- Chemistry
Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, U.K.
| | - Hau Sun Sam Chan
- Chemistry
Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, U.K.
| | - Bruno A. Sousa
- Vertex
Pharmaceuticals, 86-88
Jubilee Avenue, Milton Park, Abingdon, OX14 4RW, U.K.
| | - Kirsten E. Christensen
- Chemistry
Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, U.K.
| | - Jonathan W. Burton
- Chemistry
Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, U.K.,
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5
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Senapati S, Das S, Dixit R, Vanka K, Ramana CV. Synthesis of four diastereomers of notoryne and their 13C NMR chemical shifts analysis. J CHEM SCI 2021. [DOI: 10.1007/s12039-021-01929-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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6
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Chan HSS, Thompson AL, Christensen KE, Burton JW. Forwards and backwards - synthesis of Laurencia natural products using a biomimetic and retrobiomimetic strategy incorporating structural reassignment of laurefurenynes C-F. Chem Sci 2020; 11:11592-11600. [PMID: 34094406 PMCID: PMC8162873 DOI: 10.1039/d0sc04120c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 09/25/2020] [Indexed: 11/26/2022] Open
Abstract
Laurefurenynes C-F are four natural products isolated from Laurencia species whose structures were originally determined on the basis of extensive nuclear magnetic resonance experiments. On the basis of a proposed biogenesis, involving a tricyclic oxonium ion as a key intermediate, we have reassigned the structures of these four natural products and synthesized the four reassigned structures using a biomimetic approach demonstrating that they are the actual structures of the natural products. In addition, we have developed a synthesis of the enantiomers of the natural products laurencin and deacetyllaurencin from the enantiomer of (E)-laurefucin using an unusual retrobiomimetic strategy. All of these syntheses have been enabled by the use of tricyclic oxonium ions as pivotal synthetic intermediates.
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Affiliation(s)
- Hau Sun Sam Chan
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Amber L Thompson
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Kirsten E Christensen
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Jonathan W Burton
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
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7
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McCulley CH, Tantillo DJ. Predicting Rearrangement-Competent Terpenoid Oxidation Levels. J Am Chem Soc 2020; 142:6060-6065. [PMID: 32157874 DOI: 10.1021/jacs.9b12398] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Results of density functional theory calculations on rearrangements of potential biosynthetic precursors to the sesquiterpenoid illisimonin A reveal that only some possible precursors, those with certain specific oxidation patterns, are rearrangement-competent.
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Affiliation(s)
- Christina H McCulley
- Department of Chemistry, University of California - Davis, Davis, California 95616, United States
| | - Dean J Tantillo
- Department of Chemistry, University of California - Davis, Davis, California 95616, United States
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Taylor CA, Zhang YA, Snyder SA. The enantioselective total synthesis of laurendecumallene B. Chem Sci 2020; 11:3036-3041. [PMID: 34122807 PMCID: PMC8157515 DOI: 10.1039/c9sc06116a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 02/05/2020] [Indexed: 02/04/2023] Open
Abstract
For decades, the Laurencia family of halogenated C15-acetogenins has served as a valuable testing ground for the prowess of chemical synthesis, particularly as it relates to generating functionalized 8-membered bromoethers. Herein, we show that a readily modified and predictable approach that generates such rings and an array of attendant stereocenters via a bromenium-induced cyclization/ring-expansion process can be used to synthesize laurendecumallene B and determine the configuration of two of its previously unassigned stereocenters. In particular, this work highlights how the use of the bromenium source BDSB (Et2SBr·SbCl5Br) in non-conventional solvents is essential in generating much of the target's complexity in optimal yields and stereoselectivity. Moreover, the final structural assignment of laurendecumallene B reveals that it has one element of bromine-based chirality that, to the best of our knowledge, is not shared with any other member of the class.
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Affiliation(s)
- Cooper A Taylor
- Department of Chemistry, University of Chicago 5735 S. Ellis Avenue Chicago IL 60637 USA
| | - Yu-An Zhang
- Department of Chemistry, University of Chicago 5735 S. Ellis Avenue Chicago IL 60637 USA
| | - Scott A Snyder
- Department of Chemistry, University of Chicago 5735 S. Ellis Avenue Chicago IL 60637 USA
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Davey SG. Tricyclic oxonium tamed. Nat Rev Chem 2019. [DOI: 10.1038/s41570-019-0150-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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