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  1. Article ; Online: Strain-Inducing Positional Alkene Isomerization.

    Palani, Vignesh / Wendlandt, Alison E

    Journal of the American Chemical Society

    2023  Volume 145, Issue 36, Page(s) 20053–20061

    Abstract: Small, strained ring systems are important pharmacophores in medicinal chemistry and versatile intermediates in organic synthesis. However, the kinetic and thermodynamic instability of many strained organic molecules renders them challenging to prepare. ... ...

    Abstract Small, strained ring systems are important pharmacophores in medicinal chemistry and versatile intermediates in organic synthesis. However, the kinetic and thermodynamic instability of many strained organic molecules renders them challenging to prepare. Here, we report a strain-inducing positional alkene isomerization reaction that provides mild and selective access to cyclobutene building blocks from readily obtained cyclobutylidene precursors. This endergonic isomerization relies on the sequential and synergistic action of a decatungstate polyanion photocatalyst and cobaloxime co-catalyst to store potential energy in the form of ring strain. The versatility of the cyclobutene products is demonstrated through diverse subsequent strain-releasing transformations. Mechanistic studies reveal a steric basis for strain-selective product formation.
    Language English
    Publishing date 2023-08-30
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.3c06935
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  2. Article ; Online: Photocatalytic deracemization fixes the mix.

    Wendlandt, Alison E

    Science (New York, N.Y.)

    2019  Volume 366, Issue 6463, Page(s) 304–305

    Language English
    Publishing date 2019-10-23
    Publishing country United States
    Document type Journal Article ; Comment
    ZDB-ID 128410-1
    ISSN 1095-9203 ; 0036-8075
    ISSN (online) 1095-9203
    ISSN 0036-8075
    DOI 10.1126/science.aay6919
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  3. Article: Selective Axial-to-Equatorial Epimerization of Carbohydrates

    Carder, Hayden M. / Wang, Yong / Wendlandt, Alison E.

    Journal of the American Chemical Society. 2022 June 22, v. 144, no. 26

    2022  

    Abstract: Radical-mediated transformations have emerged as powerful methods for the synthesis of rare and unnatural branched, deoxygenated, and isomeric sugars. Here, we describe a radical-mediated axial-to-equatorial alcohol epimerization method to transform ... ...

    Abstract Radical-mediated transformations have emerged as powerful methods for the synthesis of rare and unnatural branched, deoxygenated, and isomeric sugars. Here, we describe a radical-mediated axial-to-equatorial alcohol epimerization method to transform abundant glycans into rare isomers. The method delivers highly predictable and selective reaction outcomes that are complementary to other sugar isomerization methods. The synthetic utility of isomer interconversion is showcased through expedient glycan synthesis, including one-step glycodiversification. Mechanistic studies reveal that both site- and diastereoselectivities are achieved by highly selective H atom abstraction of equatorially disposed α-hydroxy C–H bonds.
    Keywords alcohols ; isomerization ; isomers ; polysaccharides ; sugars
    Language English
    Dates of publication 2022-0622
    Size p. 11870-11877.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.2c04743
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  4. Article ; Online: Selective Axial-to-Equatorial Epimerization of Carbohydrates.

    Carder, Hayden M / Wang, Yong / Wendlandt, Alison E

    Journal of the American Chemical Society

    2022  Volume 144, Issue 26, Page(s) 11870–11877

    Abstract: Radical-mediated transformations have emerged as powerful methods for the synthesis of rare and unnatural branched, deoxygenated, and isomeric sugars. Here, we describe a radical-mediated axial-to-equatorial alcohol epimerization method to transform ... ...

    Abstract Radical-mediated transformations have emerged as powerful methods for the synthesis of rare and unnatural branched, deoxygenated, and isomeric sugars. Here, we describe a radical-mediated axial-to-equatorial alcohol epimerization method to transform abundant glycans into rare isomers. The method delivers highly predictable and selective reaction outcomes that are complementary to other sugar isomerization methods. The synthetic utility of isomer interconversion is showcased through expedient glycan synthesis, including one-step glycodiversification. Mechanistic studies reveal that both site- and diastereoselectivities are achieved by highly selective H atom abstraction of equatorially disposed α-hydroxy C-H bonds.
    MeSH term(s) Carbohydrates/chemistry ; Hexoses ; Isomerism ; Polysaccharides/chemistry ; Sugars/chemistry
    Chemical Substances Carbohydrates ; Hexoses ; Polysaccharides ; Sugars
    Language English
    Publishing date 2022-06-22
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, N.I.H., Extramural
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.2c04743
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Catalytic, contra-Thermodynamic Positional Alkene Isomerization

    Occhialini, Gino / Palani, Vignesh / Wendlandt, Alison E.

    Journal of the American Chemical Society. 2021 Dec. 30, v. 144, no. 1

    2021  

    Abstract: The positional isomerization of C═C double bonds is a powerful strategy for the interconversion of alkene regioisomers. However, existing methods provide access to thermodynamically more stable isomers from less stable starting materials. Here, we report ...

    Abstract The positional isomerization of C═C double bonds is a powerful strategy for the interconversion of alkene regioisomers. However, existing methods provide access to thermodynamically more stable isomers from less stable starting materials. Here, we report the discovery of a dual catalyst system that promotes contra-thermodynamic positional alkene isomerization under photochemical irradiation, providing access to terminal alkene isomers directly from conjugated, internal alkene starting materials. The utility of the method is demonstrated in the deconjugation of diverse electron-rich/electron-poor alkenes and through strategic application to natural product synthesis. Mechanistic studies are consistent with a regiospecific bimolecular homolytic substitution (SH2′) mechanism proceeding through an allyl-cobaloxime intermediate.
    Keywords alkenes ; catalysts ; homolytic cleavage ; irradiation ; photochemistry ; positional isomerization ; positional isomers ; regioselectivity ; thermodynamics
    Language English
    Dates of publication 2021-1230
    Size p. 145-152.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.1c12043
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  6. Article: A Change from Kinetic to Thermodynamic Control Enables trans-Selective Stereochemical Editing of Vicinal Diols

    Zhang, Yu-An / Gu, Xin / Wendlandt, Alison E.

    Journal of the American Chemical Society. 2021 Dec. 20, v. 144, no. 1

    2021  

    Abstract: Here, we report the selective, catalytic isomerization of cis-1,2-diols to trans-diequatorial-1,2-diols. The method employs triphenylsilanethiol (Ph₃SiSH) as a catalyst and proceeds under mild conditions in the presence of a photoredox catalyst and under ...

    Abstract Here, we report the selective, catalytic isomerization of cis-1,2-diols to trans-diequatorial-1,2-diols. The method employs triphenylsilanethiol (Ph₃SiSH) as a catalyst and proceeds under mild conditions in the presence of a photoredox catalyst and under blue light irradiation. The method is highly chemoselective, broadly functional group tolerant and provides concise access to trans-diol products which are not readily obtained using other methods. Mechanistic studies reveal that isomerization proceeds through a reversible hydrogen atom transfer pathway mediated by the silanethiol catalyst.
    Keywords blue light ; catalysts ; chemoselectivity ; glycols ; hydrogen ; irradiation ; isomerization ; redox reactions ; stereochemistry ; thermodynamics
    Language English
    Dates of publication 2021-1220
    Size p. 599-605.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.1c11902
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  7. Article ; Online: Selective Transformations of Carbohydrates Inspired by Radical-Based Enzymatic Mechanisms.

    Suh, Carolyn E / Carder, Hayden M / Wendlandt, Alison E

    ACS chemical biology

    2021  Volume 16, Issue 10, Page(s) 1814–1828

    Abstract: Enzymes are a longstanding source of inspiration for synthetic reaction development. However, enzymatic reactivity and selectivity are frequently untenable in a synthetic context, as the principles that govern control in an enzymatic setting often do not ...

    Abstract Enzymes are a longstanding source of inspiration for synthetic reaction development. However, enzymatic reactivity and selectivity are frequently untenable in a synthetic context, as the principles that govern control in an enzymatic setting often do not translate to small molecule catalysis. Recent synthetic methods have revealed the viability of using small molecule catalysts to promote highly selective radical-mediated transformations of minimally protected sugar substrates. These transformations share conceptual similarities with radical SAM enzymes found in microbial carbohydrate biosynthesis and present opportunities for synthetic chemists to access microbial and unnatural carbohydrate building blocks without the need for protecting groups or lengthy synthetic sequences. Here, we highlight strategies through which radical reaction pathways can enable the site-, regio-, and diastereoselective transformation of minimally protected carbohydrates in both synthetic and enzymatic systems.
    MeSH term(s) Chemistry Techniques, Synthetic/methods ; Free Radicals/chemistry ; Oligosaccharides/chemical synthesis ; Oxidation-Reduction ; Stereoisomerism ; Sugars/chemical synthesis
    Chemical Substances Free Radicals ; Oligosaccharides ; Sugars
    Language English
    Publishing date 2021-05-14
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S. ; Review
    ISSN 1554-8937
    ISSN (online) 1554-8937
    DOI 10.1021/acschembio.1c00190
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Catalytic,

    Occhialini, Gino / Palani, Vignesh / Wendlandt, Alison E

    Journal of the American Chemical Society

    2021  Volume 144, Issue 1, Page(s) 145–152

    Abstract: The positional isomerization of C═C double bonds is a powerful strategy for the interconversion of alkene regioisomers. However, existing methods provide access to thermodynamically more stable isomers from less stable starting materials. Here, we report ...

    Abstract The positional isomerization of C═C double bonds is a powerful strategy for the interconversion of alkene regioisomers. However, existing methods provide access to thermodynamically more stable isomers from less stable starting materials. Here, we report the discovery of a dual catalyst system that promotes
    Language English
    Publishing date 2021-12-30
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.1c12043
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: A Unified Strategy to Access 2- and 4-Deoxygenated Sugars Enabled by Manganese-Promoted 1,2-Radical Migration.

    Carder, Hayden M / Suh, Carolyn E / Wendlandt, Alison E

    Journal of the American Chemical Society

    2021  Volume 143, Issue 34, Page(s) 13798–13805

    Abstract: The selective manipulation of carbohydrate scaffolds is challenging due to the presence of multiple, nearly chemically indistinguishable O-H and C-H bonds. As a result, protecting-group-based synthetic strategies are typically necessary for carbohydrate ... ...

    Abstract The selective manipulation of carbohydrate scaffolds is challenging due to the presence of multiple, nearly chemically indistinguishable O-H and C-H bonds. As a result, protecting-group-based synthetic strategies are typically necessary for carbohydrate modification. Here we report a concise semisynthetic strategy to access diverse 2- and 4-deoxygenated carbohydrates without relying on the exhaustive use of protecting groups to achieve site-selective reaction outcomes. Our approach leverages a Mn
    Language English
    Publishing date 2021-08-18
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.1c05993
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: A Change from Kinetic to Thermodynamic Control Enables

    Zhang, Yu-An / Gu, Xin / Wendlandt, Alison E

    Journal of the American Chemical Society

    2021  Volume 144, Issue 1, Page(s) 599–605

    Abstract: Here, we report the selective, catalytic isomerization ... ...

    Abstract Here, we report the selective, catalytic isomerization of
    MeSH term(s) Hydrogen
    Chemical Substances Hydrogen (7YNJ3PO35Z)
    Language English
    Publishing date 2021-12-20
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.1c11902
    Database MEDical Literature Analysis and Retrieval System OnLINE

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