title: Ortho effect in the Bergman cyclization: interception of p-benzyne intermediate by intramolecular hydrogen abstraction.
abstract: Intramolecular hydrogen atom (H-atom) abstraction from the o-OCH3 group effectively intercepts the p-benzyne intermediate in the Bergman cycloaromatization of 2,3-diethynyl-1-methoxybenzene (1) before this intermediate undergoes either retro-Bergman ring opening or external H-atom abstraction. This process leads to the formation of a new diradical and renders the cyclization step essentially irreversible. Chemical and kinetic consequences of this phenomenon were investigated through the combination of computational and experimental studies.
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306-4390, USA.
authors.forename: Tarek A
authors.initials: TA
authors.lastname: Zeidan
authors.forename: Mariappan
authors.initials: M
authors.lastname: Manoharan
authors.forename: Igor V
authors.initials: IV
authors.lastname: Alabugin