Ring-Fluorinated Isoquinoline and Quinoline Synthesis: Intramolecular Cyclization of o-Cyano- and o-Isocyano-β,β-difluorostyrenes
journal contributionposted on 04.04.2003, 00:00 by Junji Ichikawa, Yukinori Wada, Hiroyuki Miyazaki, Takashi Mori, Hiroyuki Kuroki
o-Cyano-β,β-difluorostyrenes react with organolithiums selectively at the cyano carbon to generate the corresponding sp2 nitrogen anions, which in turn undergo intramolecular replacement of the vinylic fluorine to afford 3-fluoroisoquinolines. Similarly, the reaction of β,β-difluoro-o-isocyanostyrenes with organomagnesiums or -lithiums generates the corresponding sp2 carbanions on the isocyano carbon. Subsequent cyclization via substitution of the fluorine leads to 3-fluoroquinolines.