Dioxopyrrolines.XLII. : Mechanism of 7-Epimerization Reaction of 7-Substituted 5-Ethoxycarbonyl-1-phenyl-2-azabicyclo[3.2.0]heptane-3,4-diones

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7-Mono- and 7,7-disubstituted 5-ethoxycarbonyl-1-phenyl-2-azabicyclo[3.2.0]heptane-3,4-diones undergo epimerization at C-7 when treated when treated with base. Experiments using the stereospecifically deuterium labeled compound 6 showed that the inversion of stereochemistries at C-6 and C-7 took place simutaneously in this reaction, thus proving that the reaction proceeded through C_1-C_5 bond fission and recyclization. The suggested intermediate 10 with a highly strained seven membered ring would give either the C_7 epimerized product by a fast recombination or irreversibly give the dihydroazatropolones 9 by a trans- to cis- isomerization of the C=N double bond. Kinetic treatments showed that the latter reaction is slower than the former equilibrium reaction.The analogous 7-epimerization reaction observed in the hydride reduction of the 4-oxo group and in the photolysis of the imidate 24 was proved to proceed with a similar mechanism.

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Details 詳細情報について

  • CRID
    1571417127438553856
  • NII Article ID
    110003627579
  • NII Book ID
    AA00602100
  • ISSN
    00092363
  • Text Lang
    en
  • Data Source
    • CiNii Articles

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