6-(Difluoromethoxy)-1H-indazole-3-carboxylic acid synthesis

Yield:858661-80-0 26%

Reaction Conditions:

Stage #1: C₁₃H₁₂F₂N₂O₄with sodium hydroxide;water at 60; for 24 h;
Stage #2: with hydrogenchloride in water; pH=1;

Steps:

10

The ester (3.36 mmol), sodium hydroxide (10 mmol) and water (5 mL) were combined and the reaction was maintained for 24 h at 60 °C. After cooling to rt, the aqueous layer was washed with dichloromethane (3x30mL). The aqueous layer was adjusted to pH 1 with concentrated hydrochloric acid and the precipitated solids were collected by filtration, washed with water and dichloromethane, and dried to provide the acid in 26% yield.

References:

WO2005/63767,2005,A2 Location in patent:Page/Page column 50