title: Unexpected ring transformation to pyrrolo[3.2-b]pyridine derivatives. Fused azolium salts. 22.
abstract: 2-Arylsulfanyl and 2-benzylsulfanylpyridinium N-arylimides (2) easily prepared from 3-aryltetrazolopyridinium salts (1) with aryl and benzylthiolates, respectively, reacted with various dipolarophiles yielding cycloadducts that underwent transformation to give tetrahydropyrrolo[3,2-b]pyridines (5, 6, and 8) in good yields. A similar rearrangement (formation of 15) was also observed in the case of parent derivatives being unsubstituted in position 2 (12). The abscence of any significant solvent effect, comparison of the sulfur and non-sulfur analogues, as well as the stereoselective nature of the observed ring transformation seem to support a sigmatropic mechanism. Structure elucidation of the products has been carried out by single-crystal X-ray diffraction and (1)H NMR experiments.
authors.affiliation: Chemical Research Center, Institute of Chemistry, Hungarian Academy of Sciences, P.O. Box 17, H-1525 Budapest, Hungary.
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Riedl
authors.forename: Péter
authors.initials: P
authors.lastname: Kövér
authors.forename: Tibor
authors.initials: T
authors.lastname: Soós
authors.forename: György
authors.initials: G
authors.lastname: Hajós
authors.forename: Orsolya
authors.initials: O
authors.lastname: Egyed
authors.forename: László
authors.initials: L
authors.lastname: Fábián
authors.forename: András
authors.initials: A
authors.lastname: Messmer