Ortho Effect in the Bergman Cyclization: Interception of p-Benzyne Intermediate by Intramolecular Hydrogen Abstraction
摘要:
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.
Ortho Effect in the Bergman Cyclization: Interception of <i>p</i>-Benzyne Intermediate by Intramolecular Hydrogen Abstraction
作者:Tarek A. Zeidan、Mariappan Manoharan、Igor V. Alabugin
DOI:10.1021/jo051857n
日期:2006.2.1
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.