title: Preparation of new nitrogen-bridged heterocycles. 53. Syntheses of 3-(benzylthio)thieno[3,4-b]indolizine derivatives and their intramolecular arene-arene interactions.
abstract: Various ethyl 1-arylcarbonyl-3-[(un)substituted methylthio]thieno[3,4-b]indolizine-9-carboxylates were synthesized in good yields by a novel methodology in which the S-alkylation of 5-arylcarbonyl-4-ethoxycarbonylmethyl-3-(1-pyridinio)thiophene-2-thiolates with alkyl or benzyl halides, the 1,5-dipolar cyclization of the resulting pyridinium salts in the presence of a base, and the aromatization were performed. In the X-ray analyses of some 3-(benzylthio)thieno[3,4-b]indolizine-9-carboxylates, a gauche and two anti conformers in relation to the exocyclic sulfide linkage were found. Interestingly, all of the 3-(benzylthio)thieno[3,4-b]indolizine derivatives showed significant high-field shifts (delta up to 0.3 ppm) for the 5- and 6-proton signals compared with those of the 3-methylthio derivatives in the (1)H-NMR spectra and exhibited a definite absorption band near 425 nm in their UV spectra, indicating an intramolecular arene-arene interaction between the thieno[3,4-b]indolizine and the phenyl ring.
authors.affiliation: Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, Nagano, Japan. akakehi@gipwc.shinshu-u.ac.jp
authors.forename: Akikazu
authors.initials: A
authors.lastname: Kakehi
authors.forename: Suketaka
authors.initials: S
authors.lastname: Ito
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suga
authors.forename: Takeyuki
authors.initials: T
authors.lastname: Miwa
authors.forename: Takashi
authors.initials: T
authors.lastname: Mori
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Fujii
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Tanaka
authors.forename: Tomoshige
authors.initials: T
authors.lastname: Kobayashi
mesh_terms: D004347:Drug Interactions; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D007212:Indolizines / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D015394:Molecular Structure; D017672:Nitrogen Compounds / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D013678:Technology, Pharmaceutical / Q000379:methods*
chemical_list: D006571:Heterocyclic Compounds; D007212:Indolizines; D017672:Nitrogen Compounds