Pyramidalized double bonds containing endoperoxide linkages: Photooxygenation of dimethyl cis-3,8-dihydroheptalene-3,8-dicarboxylate

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Saracoglu N., Menzek A., Sayan S., Salzner U., Balci M.

JOURNAL OF ORGANIC CHEMISTRY, vol.64, no.18, pp.6670-6676, 1999 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 64 Issue: 18
  • Publication Date: 1999
  • Doi Number: 10.1021/jo990393o
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.6670-6676
  • Middle East Technical University Affiliated: No


Diels-Alder cyclo;addition utilizing singlet oxygen as the dienophile with dimethyl cis-3,8-dihydraheptalene-3,8-dicarboxylate (5) has been investigated, and monoaddition product 7 has been isolated. The addition of a second singlet oxygen to the cycloheptatriene unit in 7 gave syn-bis(norcaradiene) bis(endoperoxide) 4. H-1 NMR spectral studies and theoretical calculations indicate the increased pyramidalization in syn-4 compared with carbon analogue. The increased pyramidalization results from hyperconjugation between the central pi-bond and the four adjacent C-O bonds and by rehybridization at C3, C4, C5, and C6. Furthermore, the increased reactivity for syn-4, which is probably arising from further folding of the central double band, is also in agreement with theoretical calculations.