Get access

Kinetic Stabilization and Reactivity of π Single-Bonded Species: Effect of the Alkoxy Group on the Lifetime of Singlet 2,2-Dialkoxy-1,3-diphenyloctahydropentalene-1,3-diyls

Authors

  • Tomoyuki Nakagaki,

    1. Department of Chemistry, Graduate School of Science, Hiroshima University (HIRODAI), 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
    Search for more papers by this author
  • Tomoko Sakai,

    1. Department of Chemistry, Graduate School of Science, Hiroshima University (HIRODAI), 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
    Search for more papers by this author
  • Tsutomu Mizuta,

    1. Department of Chemistry, Graduate School of Science, Hiroshima University (HIRODAI), 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
    Search for more papers by this author
  • Yoshihisa Fujiwara,

    1. Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University (HIRODAI), 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
    Search for more papers by this author
  • Prof. Manabu Abe

    Corresponding author
    1. Department of Chemistry, Graduate School of Science, Hiroshima University (HIRODAI), 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
    2. Institute for Molecular Science (IMS), Myoudaiji, Okazaki, Aichi 444-8787 (Japan)
    • Department of Chemistry, Graduate School of Science, Hiroshima University (HIRODAI), 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
    Search for more papers by this author

Abstract

Kinetic stabilization and reactivity of π single-bonded species have been investigated in detail by generating a series of singlet 2,2-dialkoxy-1,3-diphenyloctahydropentalene-1,3-diyls (DRs). The lifetime at 293 K in benzene was found to increase when the carbon chain length of the alkoxy groups was increased; 292 ns (DRb; OR=OR′=OCH3) <880 ns (DRc; OR=OR′=OC2H5) <1899 ns (DRd; OR=OR′=OC3H7) ≈2292 ns (DRe; OR=OR′=OC6H13) ≈2146 ns (DRf; OR=OR′=OC10H21). DRh (OR=OC3H7, OR′=OCH3; 935 ns) with the mixed-acetal moiety is a longer-lived species than another diastereomer DRg (OR=OCH3, OR′=OC3H7; 516 ns). Activation parameters determined for the first-order decay process reveal that the enthalpy factor plays a crucial role in determining the energy barrier of the ring-closing reaction, that is, from the π-bonding to the σ-bonding compounds. Computational studies using density functional theory provided more insight into the structures of the singlet species with π single-bonded character and the transition states for the ring-closing reaction, thereby clarifying the role of the alkoxy group on the lifetime and the stereoselectivity of the ring-closing reaction.

Abstract

Thumbnail image of
Get access to the full text of this article

Ancillary