Used in the synthesis of a novel benzamide with potent neuroleptic activity. 5- fluoro-2-methyl-3,l-benzoxazin-4-one was obtained from 2-amino-6-fluorobenzoic acid. The condensation of 2-amino-6-fluorobenzoic acid methyl ester and (4-fluorophenyl) acetyl chloride with N,N-dimethylamino-4-pyridine in CH 2 Cl 2 to give 2-fluoro-6-[2-(4-fluoro-phenyl)-acetylamino]-benzoic acid methyl ester in 61% yield. 2 Amino 6 fluorobenzoic acid is another easily ac cessible synthon for construction of monofluorinated heterocycles. Reactions of 2,3,4,6-tetra-O-acetyl-n-D_glucopyranosyl bromide (2) with p-hydroxybenzaldehyde, trifluoromethyl and fluoro substi- tuted aniline and 2-amino-6-fluorobenzoic acid gave lO-(Pformyl- pheny1)-2,3,4,6-tetra-O-acetyl-(3-D-glucopyranoside. 2-Fluoro-6-iodobenzoic acid,a loose white crystal,was synthesized by using 2-amino-6-fluorobenzoic acid as the starting material.
The synthesis of 2-Amino-6-fluorobenzoic acid is as follows:
A 50 ml three-necked flask was charged with 1.85 g (10 mmol) of 6-fluoro-2-nitrobenzoic acid, 25.6 mg (0.2 mmol) of molybdenum dioxide, and 76.8 mg of activated carbon. 30 ml of absolute ethanol was added dropwise 1.25 g (20 mmol) of hydrazine hydrate (80%) at room temperature. After the reaction was completed at room temperature for 7 h, TLC monitoring showed that the reaction was completed, filtered, and the filtrate was concentrated, then ethyl acetate (20 mL) and water (10 ml) were added and extracted. The organic phase was washed with water and concentrated to give 1.5g desired product as a pale yellow solid, yield 96.8%, HPLC purity 99.6%.
