反应详情

To a room temperature suspension of 4-Bromo-1H-indazol-3-ol CLXXXIII (3.19 g, 15.0 mmol) in pyridine (13 ml) and H2O (20 ml) was dropwise added ethyl chloroformate (1.43 ml, 15.0 mmol). After stirring 18 hours at room temperature, the mixture was cooled to 0° C., and the precipitate was filtered and washed with cold AcOH (10 ml in 5 ml of H2O). The solid was dried in vacuo affording 4-Bromo-3-hydroxy-indazole-1-carboxylic acid ethyl ester CLXXXIV as a yellow powder (2.97 g, 69% yield).

1. temperaturethe mixture was cooled to 0° C.
2. filtrationthe precipitate was filtered
3. washwashed with cold AcOH (10 ml in 5 ml of H2O)
4. customThe solid was dried in vacuo