Experimental and Theoretical Analysis of Asymmetric Induction in Heterogeneous Catalysis: Diastereoselective Hydrogenation of Chiral α-Hydroxyketones over Pt Catalyst

I Busygin, A Taskinen, V Nieminen, E Toukoniitty, T Stillger, Reko Leino, Dmitry Murzin

    Forskningsoutput: TidskriftsbidragArtikelVetenskapligPeer review

    16 Citeringar (Scopus)

    Sammanfattning

    Assessing the origin of asymmetric induction in heterogeneously catalyzed hydrogenation is a challenging task. In this work, hydrogenation of a chiral compound, (R)-1-hydroxy-1-phenyl-2-propanone [(R)-PAC], in toluene over cinchonidine modified and unmodified Pt/Al(2)O(3) was studied. To reveal the detailed reaction mechanism and the origin of stereoselectivity in the Pt-catalyzed hydrogenation of the C = O double bond, the structures and energies of several adsorption modes of (R)-PAC as well as whole reaction paths for hydrogenation were investigated on Pt(111) by density functional theory (DFT). In agreement with experimental results, the theoretically obtained potential energy profiles for the studied hydrogenation mechanisms implied that (1R,2S)-1-phenyl-1,2-propanediol is formed in excess with respect to the other diastereomeric product diol, (1R,2R)-1-phenyl-1,2-propanediol. Generally, if the elementary hydrogen addition step was thermodynamically more favorable on one of the two diastereotopic faces, it was also kinetically preferred on the same face, and vice versa. Pairwise addition of hydrogen was the most energetically favorable mechanism. Adsorption and hydrogenation of other structurally similar chiral alpha-hydroxyketones, (R)-3-hydroxy-2-butanone and (R)-2-hydroxy-1-cyclohexanone, were also studied computationally on Pt(111). The results showed that cluster model DFT calculations can be used to assess (dia)stereoselectivity in metal-catalyzed hydrogenation of even such complex organic molecules as studied here.
    OriginalspråkOdefinierat/okänt
    Sidor (från-till)4449–4462
    Antal sidor14
    TidskriftJournal of the American Chemical Society
    Volym131
    Utgåva12
    DOI
    StatusPublicerad - 2009
    MoE-publikationstypA1 Tidskriftsartikel-refererad

    Citera det här