Transformation of octadehydrodibenzo[12]annulene to benzonaphthopentalene by successive nucleophilic and electrophilic transannular cyclizations

Shunpei Nobusue, Ayumi Yoshizaki, Masahito Miki, Hirokazu Miyoshi, Akihiro Shimizu, Tobe Yoshito*

*Corresponding author for this work

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

A nucleophile-induced cyclization of octadehydrodibenzo[12]annulene derivative 1b was investigated. Treatment of 1b with BuLi gave fused 5-9-membered ring products, dibenzobicyclo[7.3.0]tetraenediynes 2a and 2b, formed via a single transannular cyclization reaction. The reason why double cyclization did not occur is ascribed to the structure of a plausible anionic intermediate in which a negative charge locates apart from the remaining triple bond carbons. The second cyclization did not take place even when once-isolated product 2b was treated with BuLi because of the higher reactivity toward a nucleophile of the fulvene moiety compared to the triple bonds. On the other hand, heating a chlorobenzene solution of 2b containing cyclohexa-1,4-diene gave products 3a-c possessing a benzonaphthopentalene framework via a Bergman cyclization pathway albeit in low yields after inter- or intramolecular hydrogen abstraction. Moreover, iodine-induced transannular cyclization of 2b afforded the corresponding diiodide 3d.

Original languageEnglish
Pages (from-to)8474-8479
Number of pages6
JournalTetrahedron
Volume70
Issue number45
DOIs
StatePublished - 11 Nov 2014

Keywords

  • Benzonaphthopentalene
  • Dehydrobenzoannulenes
  • Dibenzobicyclo[7.3.0]tetraenediyne
  • Transannular cyclization

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