Synthesis and unusual properties of highly strained anthracenophanes

Tobe Yoshito*

*Corresponding author for this work

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Aromatic character of small-bridged cyclophanes of condensed benzenoid aromatics would be more sensitive to strain than that of the corresponding [n]paracyclophanes. In this context, we synthesized [6](1,4)anthracenophanes and [6](9,10)anthracenophanes, the smallest anthracenophanes thus far known, and investigated their structures and reactivities. Syntheses of these highly strained molecules were undertaken via two routes; one based on cleavage of the central bond of the [6.2.2]propellane skeleton and the other using benzoannelation to the [6]paracyclophane core. The parent 9,10-bridged anthracene was fully characterized but it is too kinetically unstable for isolation, while the perisubstituted derivatives are stable owing to the steric protection. X-ray crystallographic structure analyses of the anthracenophanes revealed remarkable out-of-plane deformation of the bridged ring of the 9,10-bridged anthracenes, but also notable bond length alternation in the 1,4-bridged anthracene. 1H-NMR spectra indicate, however, that they retain aromaticity in spite of the severe distortion of the aromatic ring. Unusual reactivities were observed in particular in the electrophilic reactions of the 1,4 -bridged anthracene such as acid-catalyzed telomerization, addition reactions to dienophiles presumably via zwitterion intermediates, and photochemical [2+2] dimerization. 9,10-Bridged anthracenes underwent acid-catalyzed and photochemical isomerizations, giving methylenedihydroanthracenes and 9,10-Dewar anthracenes, respectively.

Original languageEnglish
Pages (from-to)610-618
Number of pages9
JournalYuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry
Volume55
Issue number7
DOIs
StatePublished - 1 Jan 1997

Keywords

  • Acid-catalyzed telomerization
  • Aromaticity
  • Bond length alternation
  • Cyclophane
  • Dienophile
  • Out-of-plane deformation
  • Photodimerization
  • Steric protection
  • Strain
  • Valence isomerization

Fingerprint Dive into the research topics of 'Synthesis and unusual properties of highly strained anthracenophanes'. Together they form a unique fingerprint.

  • Cite this