Sodium Nitrite → Ethyl 6-hydroxybenzo[d]isoxazole-3-carboxylate

Ethyl 6-aminobenzo[d]isoxazole-3-carboxylate (2.43 mmol) was diluted with a solution of sulfuric acid (2.5 mL) in water (2.5 mL) and the resulting mixture was maintained at rt for 30 min. A solution of sodium nitrite (2.67 mmol) in water (2.5 ml) was added dropwise at 0° C. and the resulting mixture was maintained for 30 min at 0° C. This aqueous solution was added to a cold (0° C.) solution of copper (II) nitrate (149 mmol) in water (80 mL) and the reaction mixture was allowed to warm to rt. After 5 min., copper (I) oxide (2.78 mmol) was added to the mixture and the reaction mixture was maintained for 1 h at rt. The reaction mixture was extracted with ethyl acetate (3×100 mL) and the combined organic layers were dried (magnesium sulfate) and concentrated to provide crude ethyl 6-hydroxybenzo[d]isoxazole-3-carboxylate in 99% yield as a brown oil.

1. temperaturethe resulting mixture was maintained for 30 min at 0° C
2. temperatureto warm to rt
3. temperaturethe reaction mixture was maintained for 1 h at rt
4. extractionThe reaction mixture was extracted with ethyl acetate (3×100 mL)
5. dry with materialthe combined organic layers were dried (magnesium sulfate)
6. concentrationconcentrated

ORD-Eintrag

ord-1e63a6fec163400da8771ee4e39e7b56

Quelldatensatz

uspto-grants-2012_01

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08106066B2