title: Reaction of azulenes with 1-trifluoromethanesulfonylpyridinium trifluoromethanesulfonate (TPT) and synthesis of the parent azulene.
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.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Shunji
authors.initials: S
authors.lastname: Ito
authors.forename: Ryuji
authors.initials: R
authors.lastname: Yokoyama
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Okujima
authors.forename: Tomomi
authors.initials: T
authors.lastname: Terazono
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kubo
authors.forename: Akio
authors.initials: A
authors.lastname: Tajiri
authors.forename: Masataka
authors.initials: M
authors.lastname: Watanabe
authors.forename: Noboru
authors.initials: N
authors.lastname: Morita
mesh_terms: D052176:Azulenes; D003508:Cycloheptanes / Q000138:chemical synthesis / Q000737:chemistry*; D008698:Mesylates / Q000737:chemistry*; D011726:Pyridinium Compounds / Q000737:chemistry*
chemical_list: D052176:Azulenes; D003508:Cycloheptanes; D008698:Mesylates; D011726:Pyridinium Compounds; C005525:azulene; C012077:trifluoromethanesulfonic acid