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Zheng H, Wang K, De Angelis L, Arman HD, Doyle MP. Brønsted Acid Catalyzed Oxocarbenium-Olefin Metathesis/Rearrangements of 1 H-Isochromene Acetals with Vinyl Diazo Compounds. J Am Chem Soc 2021; 143:15391-15399. [PMID: 34510888 DOI: 10.1021/jacs.1c07271] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
An oxocarbenium-olefin cross metathesis occurs during Brønsted acid catalyzed reactions of 1H-isochromene acetals with vinyl diazo compounds. Formally a carbonyl-alkene [2 + 2]-cyclization between isobenzopyrylium ions and the vinyl group of vinyl diazoesters, the retro-[2 + 2] cycloaddition produces a tethered alkene and a vinyl diazonium ion that, upon loss of dinitrogen, undergoes a highly selective carbocationic cascade rearrangements to diverse products whose formation is controlled by reactant substituents. Polysubstituted benzobicyclo[3.3.1]oxocines, benzobicyclo[3.2.2]oxepines, benzobicyclopropane, and naphthalenes are obtained in good to excellent yields and selectivities. Furthermore, isotopic tracer and control experiments shed light on the oxocarbenium-olefin metathesis/rearrangement process as well as on the origin of the interesting substituent-dependent selectivity.
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Affiliation(s)
| | | | | | | | - Michael P Doyle
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas 78249, United States
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2
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Howard EM, Brewer M. A Lewis Acid-Catalyzed Diastereoselective Synthesis of Functionalized 2-Diazo-1,5-dicarbonyl Compounds. ACS Catal 2021. [DOI: 10.1021/acscatal.1c03036] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Evan M. Howard
- Department of Chemistry, The University of Vermont, 82 University Place, Burlington, Vermont 05405, United States
| | - Matthias Brewer
- Department of Chemistry, The University of Vermont, 82 University Place, Burlington, Vermont 05405, United States
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3
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Hassan AA, Oscarson S. A General Method for the Divergent Synthesis of C‐9 Functionalised Sialic Acid Derivatives. European J Org Chem 2020. [DOI: 10.1002/ejoc.202001049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Abdullah A. Hassan
- Centre for Synthesis and Chemical Biology University College Dublin Dublin 4 Ireland
| | - Stefan Oscarson
- Centre for Synthesis and Chemical Biology University College Dublin Dublin 4 Ireland
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4
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Fang J, Howard EM, Brewer M. A Conjugate Addition Approach to Diazo-Containing Scaffolds with β Quaternary Centers. Angew Chem Int Ed Engl 2020; 59:12827-12831. [PMID: 32365265 PMCID: PMC11157584 DOI: 10.1002/anie.202004557] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 04/28/2020] [Indexed: 01/25/2023]
Abstract
Structurally complex diazo-containing scaffolds are formed by conjugate addition to vinyl diazonium salts. The electrophile, a little studied α-diazonium-α,β-unsaturated carbonyl compound, is formed at low temperature under mild conditions by treating β-hydroxy-α-diazo carbonyls with Sc(OTf)3 . Conjugate addition occurs selectively at the 3-position of indole to give α-diazo-β-indole carbonyls, and enoxy silanes react to give 2-diazo-1,4-dicarbonyl products. These reactions result in the formation of tertiary and quaternary centers, and give products that would be otherwise difficult to form. Importantly, the diazo functional group is retained within the molecule for future manipulation. Treating an α-diazo ester indole addition product with Rh2 (OAc)4 caused a rearrangement to occur to give a 2-(1H-indol-3-yl)-2-enoate. In the case of diazo ketone compounds, this shift occurred spontaneously on prolonged exposure to the Lewis acidic reaction conditions.
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Affiliation(s)
- Jian Fang
- Department of Chemistry, University of Vermont, Innovation Hall, 82 University Place, Burlington, VT, 05495, USA
| | - Evan M Howard
- Department of Chemistry, University of Vermont, Innovation Hall, 82 University Place, Burlington, VT, 05495, USA
| | - Matthias Brewer
- Department of Chemistry, University of Vermont, Innovation Hall, 82 University Place, Burlington, VT, 05495, USA
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5
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Fang J, Howard EM, Brewer M. A Conjugate Addition Approach to Diazo‐Containing Scaffolds with β Quaternary Centers. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004557] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Jian Fang
- Department of Chemistry University of Vermont Innovation Hall, 82 University Place Burlington VT 05495 USA
| | - Evan M. Howard
- Department of Chemistry University of Vermont Innovation Hall, 82 University Place Burlington VT 05495 USA
| | - Matthias Brewer
- Department of Chemistry University of Vermont Innovation Hall, 82 University Place Burlington VT 05495 USA
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6
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Hawsawi M, Pirrone MG, Wickramasinghe A, Crich D. Use of hydroxylamines, hydroxamic acids, oximes and amines as nucleophiles in the Zbiral oxidative deamination of N-acetyl neuraminic acid. Isolation and characterization of novel mono- and disubstitution products. Carbohydr Res 2020; 490:107921. [PMID: 32171977 PMCID: PMC7250565 DOI: 10.1016/j.carres.2020.107921] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/20/2020] [Accepted: 01/20/2020] [Indexed: 12/14/2022]
Abstract
The oxidative deamination of N-nitroso N-acetylneuraminic acid (NeuAc) derivatives is a useful reaction for the formation of 5-desamino-5-hydroxy NeuAc derivatives and their stereoisomers. We demonstrated previously that replacement of the classical nucleophile in these reactions, acetic acid, by phenols resulted in a novel double displacement process with substitution of the acetoxy group at the 4-position taking place in addition to that of the 5-acetamido group, for which we postulated a mechanism centered on the formation of a highly reactive vinyl diazonium ion. We now extend these studies to encompass the use of hydroxylamine-based systems and weakly basic amines as nucleophile. We find that the nature of the product depends significantly on the pKa of the nucleophile, with the more acidic species typically affording only substitution at the 5-position, while the less acidic species give mixtures of elimination products and disubstitution products. The use of aniline as nucleophile is of particular note as it affords a novel aziridine spanning positions 4- and 5- of the neuraminic acid skeleton.
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Affiliation(s)
- Mohammed Hawsawi
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA
| | - Michael G Pirrone
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA; Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, GA, 30602, USA
| | - Anura Wickramasinghe
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA; Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, GA, 30602, USA.
| | - David Crich
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA; Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, GA, 30602, USA; Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, GA, 30602, USA; Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA.
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7
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Sarpe VA, Crich D. Oxidative deamination of amino sugars: recent advances. CARBOHYDRATE CHEMISTRY 1979; 72:312-314. [PMID: 34290849 PMCID: PMC8291039 DOI: 10.1016/s0008-6215(00)83957-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
An overview of the oxidative deamination of N-acetylneuraminic acid derivatives (Neu5Ac) leading to the formation of ketodeoxynonulosonic acid (KDN), its stereoisomers and glycosides is presented. A brief historical introduction to the deamination is given, followed by a description of recent advances in reaction conditions, which have allowed application of the process to Neu5Ac thioglycosides, and that have enabled the range of nucleophiles incorporated in the course of the reaction to be extended beyond the original acetate and azide. Recent advances resulting in derivatization of the Neu55Ac 4-position concomitant with replacement of the acetamido group, via the presumed intermediacy of a vinyl diazonium ion, are then described. The literature on the mechanism of the deamination reaction is next considered leading to the presentation of an overall mechanistic framework that accounts for all observations to date. Finally, the application of the deamination reaction to complex Neu5Ac-based oligosaccharides and other aminosugars is presented.
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Affiliation(s)
- Vikram A Sarpe
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, GA 30602, USA
- Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - David Crich
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, GA 30602, USA
- Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
- Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, GA 30602, USA
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