Benzoic acid, 3-borono-5-hydroxy- (9CI) synthesis

Yield:851667-21-5 27%

Reaction Conditions:

Stage #1: 3-amino-5-carboxylphenylboronic acid hydrochloridewith sulfuric acid;sodium nitrite in water at -5; for 1 h;
Stage #2: with water at 60;

Steps:

1.6

(3-carboxy-5-hydroxyphenyl) boronic acid (FL-172) To make the desired compound, 3-amino-5-carboxylphenylboronic acid hydrochloride (22 mg, 0.1 mmol) was suspended in 2 mL of 50% H2S04 and treated at -5°C with a solution of NaNO2 (8 mg, 0.1 mmol) in 1 mL of water. After the mixture had been stirred for 1 h at this temperature, water (10 mL) was added and the mixture was warmed to 60 °C until the evolution of gas ceased. The dark brown solution was extracted twice with ether, and the extracts'were washed with water and brine and dried with Na2SO4. The solvent was evaporated to dryness, then the residue was recrystallized from methanol to give 5 mg (27% yield) of the desired compound as a pale yellow powder

References:

WO2005/41904,2005,A2 Location in patent:Page/Page column 277