7,8-Difluoro-4-hydroxyquinoline-3-carboxylic acid synthesis

Yield:-

Reaction Conditions:

with lithium hydroxide;acetic acid in tetrahydrofuran;methanol;

Steps:

6 7,8-Difluoro-4-hydroxy-3-quinolinecarboxylic acid STR58

PREPARATION 6 7,8-Difluoro-4-hydroxy-3-quinolinecarboxylic acid STR58 To a suspension of 2.0 g of ethyl 7,8-difluoro-4-hydroxy-3-quinolinecarboxylate (Magn. Reson. Chem., 34, 972-978 (1996)) in 160 mL of a 1:1 (v/v) mixture of methanol and tetrahydrofuran is added 40 mL of a 1.0 M aqueous solution of lithium hydroxide. After three days the volume of the solution is reduced by two-thirds by evaporation at reduced pressure. Twenty percent aqueous acetic acid is added to the solution until further addition causes no additional precipitate to form. The precipitate is collected by filtration and it is washed with three successive 50 mL portions of distilled water. The solid is dried at 75° C. and 20 torr for 18 h. This procedure yields the title compound as 1.54 g of a white solid.

References:

US6093732,2000,A