Articles producció científica> Química Física i Inorgànica

Understanding the mechanism of transition metalfree anti addition to alkynes: the selenoboration case

  • Identification data

    Identifier: PC:3382
    Authors:
    Ricart, J. M.García-López, D.Civit, M.Vogels, C.Westcott, S.Fernández, E.Carbó, J.
    Abstract:
    The stereoselective anti-addition of selenoboranes to α,β-acetylenic esters and amides was achieved in a transition metal-free context using catalytic amounts of PCy3. The reaction provides anti-3,4- selenoboration with concomitant delivery of α-vinyl selenides by protodeboronation with MeOH. Interestingly, in the absence of phosphine the selenoboration switches towards the formation of β-vinyl selenides. Theoretical calculations rationalize the regio- and stereoselectivity of the reaction by discovering a new mechanism for the anti-3,4-selenoboration. While the selenoborane is activated via the “push–pull” effect of B, the phosphine interacts with the β position of the alkynoate switching the polarity of the triple bond and favoring 1,3-selenoboration which provides the α-addition of the selenyl group. Then, the autocatalytic action of a second selenoborane reagent, which coordinates to the phosphorus ylide intermediate, determines the stereoselectivity and completes the catalytic process. Finally, the comparison of selenoborane reagents with diboranes and silaboranes, which have exhibited analogous reactivity, shows that the selenium moiety has a larger nucleophilic character favoring the performance of the reaction under mild conditions.
  • Others:

    Author, as appears in the article.: Ricart, J. M. ; García-López, D.; Civit, M.; Vogels, C. ; Westcott, S. ; Fernández, E. ; Carbó, J.
    Department: Química Física i Inorgànica
    URV's Author/s: RICART PLA, JOSE MANUEL; García-López, D.; Civit, M.; Vogels, C. ; Westcott, S. ; FERNÁNDEZ GUTIÉRREZ, MARIA ELENA; CARBÓ MARTIN, JORGE JUAN
    Keywords: selenoboration stereoselective anti-addition
    Abstract: The stereoselective anti-addition of selenoboranes to α,β-acetylenic esters and amides was achieved in a transition metal-free context using catalytic amounts of PCy3. The reaction provides anti-3,4- selenoboration with concomitant delivery of α-vinyl selenides by protodeboronation with MeOH. Interestingly, in the absence of phosphine the selenoboration switches towards the formation of β-vinyl selenides. Theoretical calculations rationalize the regio- and stereoselectivity of the reaction by discovering a new mechanism for the anti-3,4-selenoboration. While the selenoborane is activated via the “push–pull” effect of B, the phosphine interacts with the β position of the alkynoate switching the polarity of the triple bond and favoring 1,3-selenoboration which provides the α-addition of the selenyl group. Then, the autocatalytic action of a second selenoborane reagent, which coordinates to the phosphorus ylide intermediate, determines the stereoselectivity and completes the catalytic process. Finally, the comparison of selenoborane reagents with diboranes and silaboranes, which have exhibited analogous reactivity, shows that the selenium moiety has a larger nucleophilic character favoring the performance of the reaction under mild conditions.
    Research group: Química Quàntica
    Thematic Areas: Química Química Chemistry
    licence for use: https://creativecommons.org/licenses/by/3.0/es/
    ISSN: 2044-4753
    Author identifier: 0000-0002-2610-5535; ; ; ; ; 0000-0001-9025-1791; 0000-0002-3945-6721
    Record's date: 2019-01-25
    Last page: 3628
    Journal volume: 8
    Papper version: info:eu-repo/semantics/publishedVersion
    Link to the original source: https://pubs.rsc.org/en/content/articlelanding/2018/CY/C7CY02295F#!divAbstract
    Funding program: plan; Excelencia; CTQ2016-80328-P plan; Excelencia; CTQ2014-52774-P altres; Grupos consolidados; 2014SGR199
    Licence document URL: https://repositori.urv.cat/ca/proteccio-de-dades/
    Article's DOI: 10.1039/c7cy02295f
    Entity: Universitat Rovira i Virgili
    Journal publication year: 2018
    First page: 3617
    Publication Type: Article Artículo Article
  • Keywords:

    Metalls de transició
    Bor
    Estereoquímica
    selenoboration
    stereoselective anti-addition
    Química
    Química
    Chemistry
    2044-4753
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