Stoichiometric C[BOND]H Bond Cleavage Reaction in a Bis(carboxylato)ruthenium(II) Complex and Its Application to the Catalytic H–D Exchange Reaction of Carboxylic Acids

Authors

  • Prof. Masafumi Hirano,

    Corresponding author
    1. Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Kongai, Tokyo 184-8588 (Japan), Fax: (+81) 423-887-044 (MH), (+81) 423-887-043 (SK), (MH), (SK)
    • Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Kongai, Tokyo 184-8588 (Japan), Fax: (+81) 423-887-044 (MH), (+81) 423-887-043 (SK), (MH), (SK)
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  • Ryo Fujimoto,

    1. Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Kongai, Tokyo 184-8588 (Japan), Fax: (+81) 423-887-044 (MH), (+81) 423-887-043 (SK), (MH), (SK)
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  • Kohei Hatagami,

    1. Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Kongai, Tokyo 184-8588 (Japan), Fax: (+81) 423-887-044 (MH), (+81) 423-887-043 (SK), (MH), (SK)
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  • Nobuyuki Komine,

    1. Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Kongai, Tokyo 184-8588 (Japan), Fax: (+81) 423-887-044 (MH), (+81) 423-887-043 (SK), (MH), (SK)
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  • Prof. Sanshiro Komiya

    Corresponding author
    1. Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Kongai, Tokyo 184-8588 (Japan), Fax: (+81) 423-887-044 (MH), (+81) 423-887-043 (SK), (MH), (SK)
    • Department of Applied Chemistry, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Kongai, Tokyo 184-8588 (Japan), Fax: (+81) 423-887-044 (MH), (+81) 423-887-043 (SK), (MH), (SK)
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Abstract

A cationic complex [Ru{OC(O)CMe[DOUBLE BOND]CH22O,O′}(PMe3)4]+CH2[DOUBLE BOND]CMeCO2 (5 a) and its related carboxylato complexes are newly prepared by the reaction of [cis-RuH2(PMe3)4] (4) with carboxylic acids in methanol in 76–100 % yield. Complex 5 a reversibly transforms to the neutral form [cis-Ru{OC(O)CMe[DOUBLE BOND]CH21O}2(PMe3)4] (2 a) in nonpolar solvents. Complex 2 a reversibly liberates a PMe3 group to give [Ru{OC(O)CMe[DOUBLE BOND]CH21O}{OC(O)CMe[DOUBLE BOND]CH22O,O′}(PMe3)3] (12 a) from which a stereoselective C[BOND]H bond cleavage reaction occurs to give a ruthenalactone [Ru{OC(O)CMe[DOUBLE BOND]CH-κ2O,C}(PMe3)4] (1 a) from the release of methacrylic acid. Complexes 2 a and 5 a also give 1 a but the prior dissociation of a PMe3 is indispensable for the C[BOND]H bond cleavage reaction. Complex 1 a establishes an equilibrium with 2 a (or 5 a) in solution. In this reaction, one coordinated carboxylato ligand is engaged in the C[BOND]H bond cleavage reaction as a proton acceptor, but neither the added carboxylato anion nor typical proton acceptors such as proton sponge assist the reaction. In [D4]MeOH, a catalytic stereospecific deuteration of carboxylic acids has been achieved by 4, in which the equilibrium between 5 a and 1 a plays a key role.

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