An improved access to 4-trifluoromethyl-2(1H)-quinolinones: The "watering protocol"

Condensation of anilines with Et 4,4,4-trifluoroacetoacetate to afford the corresponding 4,4,4-trifluoro-3-oxobutaneanilides, precursors to 4-(trifluoromethyl)-2-quinolinones, can be favored and the competing condensation to produce the Et 4,4,4-trifluoro-3-(phenylimino)butanoate, the precursor to 2-(trifluoromethyl)-4-quinolinones, avoided if water is occasionally added to the reaction mixt. while ethanol is continuously removed by distn. The 4,4,4-trifluoro-3-oxobutaneanilides also form selectively when 4,4,4-trifluoroacetoacetyl chloride is allowed to react with anilines. The cyclization of the anilides has to be accomplished under carefully controlled conditions. The resulting 4-(trifluoromethyl)-2-quinolinones can be converted into 4-(trifluoromethyl)quinolines, 4-(trifluoromethyl)-2-quinolinecarboxylic acids, and 2-bromo-4-(trifluoromethyl)quinolines, the last of which may in turn be converted into 2-bromo-4-(trifluoromethyl)-3-quinolinecarboxylic acids and eventually 4-trifluoromethyl-3-quinolinecarboxylic acids. [on SciFinder (R)]