A simple facile synthesis of bifluorenylidenes

Amalia Levy, Michal Goldschmidt, Israel Agranat

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Bifluorenylidenes were synthesized in two steps, by conversion of fluorenones to fluorenethiones followed by reductive dimerization of the latter in boiling benzene. Treatment of 12H-dibenzo[b,h]fluoren-12-one (5) with Lawesson's reagent (LR) in boiling toluene gave12H-dibenzo[b,h]fluorene-12-thione (6). Heating a benzene solution of 6 under reflux gave 12-(12'H-dibenzo[b,h]fluorene-12'-ylidene)-12H-dibenzo[b,h] fluorene (4) in 65% yield. (E)-and (Z)- 11-(11'H-benzo[b]fluorene-11'-ylidene)-11H-benzo[b]fluorene were prepared analogously. The method was applied also to the synthesis of the cross coupling product 9-(11'H-benzo [b]fluorene-1l'-ylidene)- 9H- fluorene (12). A mechanism of the reductive dimerization of thione 6 via its dimer 17 and carbene 16 leading to 4 was outlined.

Original languageEnglish
Pages (from-to)579-584
Number of pages6
JournalLetters in Organic Chemistry
Volume3
Issue number8
DOIs
StatePublished - 1 Aug 2006
Externally publishedYes

Keywords

  • Biflourenylidene
  • Bistricyclic aromatic enes
  • Lawesson's reagent
  • Overcrowding
  • Reductive dimerization
  • Thioketones

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