3-Fluoro-2-quinolones From Anilines

N-(Fluoro-3-methoxyacryloyl)anilines [2-fluoro-3-methoxy-2-propenanilides] can be prepd. by condensation between lithium anilides and Me 2-fluoro-3-methoxy-2-propenoate. For example, the reaction of (E)- and (Z)-2-fluoro-3-methoxy-2-propenoic acid Me ester with aniline gave (E)- and (Z)-2-fluoro-3-methoxy-N-phenyl-2-propenoic acid Me ester. The cyclocondensation of the latter gave 3-fluoro-2(1H)-quinolinone. Under strongly acidic conditions, these intermediate undergo a cyclization reaction accompanied by elimination of methanol to give 3-fluoro-2-quinolones. Substituents occupying the para or ortho position of the aniline appear at the heterocyclic 6- and 8-positions, resp. In general, substituents attached to the meta position of the aniline lead to 1:1 mixts. of regioisomers. Only m-anisidine [3-methoxy-aniline] and m-fluoroaniline made an exception: they gave mainly the 7- and only trace amts. of the 5-substituted quinolone. [on SciFinder (R)]