Ring-fluorinated isoquinoline and quinoline synthesis: intramolecular cyclization of o-cyano- and o-isocyano-beta,beta-difluorostyrenes.

o-Cyano-beta,beta-difluorostyrenes react with organolithiums selectively at the cyano carbon to generate the corresponding sp(2) nitrogen anions, which in turn undergo intramolecular replacement of the vinylic fluorine to afford 3-fluoroisoquinolines. Similarly, the reaction of beta,beta-difluoro-o-isocyanostyrenes with organomagnesiums or -lithiums generates the corresponding sp(2) carbanions on the isocyano carbon. Subsequent cyclization via substitution of the fluorine leads to 3-fluoroquinolines. [reaction: see text]