title: Transformation of Zwitterionic Pyridine Derivatives to a Spiro-Fused Ring System: Azoniabenzo[de]fluorine. Synthesis and Mechanistic Rationalization.
abstract: Reaction of aryl- and benzylsulfanopyridinium amidates bearing a methyl group in position 6 with 2 equiv of diphenylketene afforded a spiro-fused ring system: azoniabenzo[de]fluorine. By use of an excess amount of ketene, a distinct reaction was observed via which a 1H-pyrrolo[3,2-b]pyridin-2(3H)-one derivative was furnished. The structure of the tetracyclic spiro-fused ring system was unambiguously confirmed by X-ray diffraction, and its formation was rationalized by DFT calculations.
authors.affiliation: Research Centre for Natural Sciences, Institute of Organic Chemistry, Hungarian Academy of Sciences, Magyar tudósok körútja 2, H-1117 Budapest, Hungary.
authors.forename: Roberta
authors.initials: R
authors.lastname: Palkó
authors.affiliation: Research Centre for Natural Sciences, Institute of Organic Chemistry, Hungarian Academy of Sciences, Magyar tudósok körútja 2, H-1117 Budapest, Hungary.
authors.forename: Orsolya
authors.initials: O
authors.lastname: Egyed
authors.affiliation: Research Centre for Natural Sciences, Institute of Organic Chemistry, Hungarian Academy of Sciences, Magyar tudósok körútja 2, H-1117 Budapest, Hungary.
authors.forename: Tibor András
authors.initials: TA
authors.lastname: Rokob
authors.affiliation: Research Centre for Natural Sciences, Institute of Organic Chemistry, Hungarian Academy of Sciences, Magyar tudósok körútja 2, H-1117 Budapest, Hungary.
authors.forename: Petra
authors.initials: P
authors.lastname: Bombicz
authors.affiliation: Research Centre for Natural Sciences, Institute of Organic Chemistry, Hungarian Academy of Sciences, Magyar tudósok körútja 2, H-1117 Budapest, Hungary.
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Riedl
authors.affiliation: Research Centre for Natural Sciences, Institute of Organic Chemistry, Hungarian Academy of Sciences, Magyar tudósok körútja 2, H-1117 Budapest, Hungary.
authors.forename: György
authors.initials: G
authors.lastname: Hajós