title: Preparation of new nitrogen-bridged heterocycles. 60. Syntheses and conformational analyses of bis(indolizin-1-yl) disulfides.
abstract: Some bis(indolizin-1-yl) disulfides, readily obtainable from the treatment of 1-(benzoylthio)indolizines with piperidine, were prepared and their conformations were investigated. In comparison with those of 1-(benzoylthio)indolizines, the (1)H-NMR spectra of these disulfides showed considerable high field shifts (delta 0.13-0.82 ppm) on each pyridine ring proton and the UV spectra exhibited significant bathochromic and hyperchromic shifts. These results supported strongly the participation of an intramolecular pi-pi interaction between the two indolizine rings in these molecules and, hence, of a particular gauche (cis) conformation. However, the conformational considerations and molecular calculations (Mopac PM3) for some bis(indolizin-1-yl) disulfides showed the presence of four more stable gauche forms in which two are enantiomeric, resulting in three types of gauche structures. These three types of gauche structures were confirmed by X-ray analyses.
authors.affiliation: Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, Nagano, Japan. akakehi@shinshu-u.ac.jp
authors.forename: Akikazu
authors.initials: A
authors.lastname: Kakehi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suga
authors.forename: Hiroko
authors.initials: H
authors.lastname: Okuno
authors.forename: Masaki
authors.initials: M
authors.lastname: Okuhara
authors.forename: Akira
authors.initials: A
authors.lastname: Ohta
mesh_terms: D000465:Algorithms; D018360:Crystallography, X-Ray; D004220:Disulfides / Q000737:chemistry*; D006572:Heterocyclic Compounds, Bridged-Ring / Q000138:chemical synthesis* / Q000494:pharmacology; D007212:Indolizines / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D009584:Nitrogen / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism
chemical_list: D004220:Disulfides; D006572:Heterocyclic Compounds, Bridged-Ring; D007212:Indolizines; C035094:indolizine; D009584:Nitrogen