Preparation of new nitrogen-bridged heterocycles. 54.1) Increased arene-arene interactions of 3-(bicyclic and tricyclic arylmethylthio)thieno[3,4-b]indolizine derivatives

Abstract

Some thieno[3,4-b]indolizine derivatives having a 1-naphthylmethylthio, 2-methyl-1-naphthylmethylthio, 2-naphthylmethylthio, or 9-anthrylmethylthio group at the 3-position were prepared and their intramolecular arene-arene interactions were investigated. In comparison with 3-(methylthio)thieno[3,4-b] indolizines which have no such interactions, the 1H-NMR spectra of title compounds showed large high-field shifts (δ 0.06-0.89 ppm) for the protons of the pyridine ring in the thieno[3,4-b]indolizine, and these values were considerably larger than those (δ<0.3 ppm) in 3-(benzylthio) thieno[3,4-b]indolizines. The UV spectra also exhibited a characteristic absorption band near 425 nm attributable to the arene-arene interaction. In the X-ray analyses of some compounds, however, the presence of both the gauche and the anti conformers at the sulfide spacer were confirmed. © 2003 Pharmaceutical Society of Japan.