Reaction of azulenes with 1-trifluoromethanesulfonylpyridinium trifluoromethanesulfonate (TPT) and synthesis of the parent azulene

Org Biomol Chem. 2003 Jun 7;1(11):1947-52. doi: 10.1039/b212484j.

Abstract

2-Azulenyl trifluoromethanesulfonate was prepared by the reaction of 2-hydroxyazulene with trifluoromethanesulfonic anhydride in the presence of triethylamine as a base. Under the use of pyridine, 1-trifluoromethanesulfonylpyridinium trifluoromethanesulfonate further reacted with 2-azulenyl trifluoromethanesulfonate to give 1-(1-trifluoromethanesulfonyl-1,4-dihydropyridin-4-yl)azulenyl trifluoromethanesulfonate. Moreover, we found that azulenes also reacted with 1-trifluoromethanesulfonylpyridinium trifluoromethanesulfonate to give 4-(1-azulenyl)-1,4-dihydropyridine derivatives and 6-(1-azulenyl)-1-trifluoromethanesulfonyl-1-aza-hexa-1,3,5-triene depending on the reaction conditions. 2-Azulenyl trifluoromethanesulfonate was converted finally into the parent azulene in excellent yield by palladium-catalyzed reduction using formic acid as a reducing reagent.

MeSH terms

  • Azulenes
  • Cycloheptanes / chemical synthesis
  • Cycloheptanes / chemistry*
  • Mesylates / chemistry*
  • Pyridinium Compounds / chemistry*

Substances

  • Azulenes
  • Cycloheptanes
  • Mesylates
  • Pyridinium Compounds
  • azulene
  • trifluoromethanesulfonic acid