3-Hydroxy-1-naphthoic acid → 4-Amino-3-hydroxynaphthalene-1-carboxylic acid

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Reaction Conditions

Reaction Steps

To a stirred solution of p-benzenediazonium sulfonate, which was prepared by the addition of sodium sulfanilate (0.525 g, 2.7 mmole) to sodium nitrite at 0°, and the compound from example 14 c) (0.413 g, 2.2 mmol) in water (20 mL), sodium bicarbonate (2.3 g, 27.0 mmol) was added slowly. The resulting solution was heated at 60° C. with stirring overnight. After the solution was cooled to 50° C., sodium hydrogen sulfite (1.05 g, 6.0 mmole) was added. The resulting solution was stirred for 30 min. at 50° C. After cooling down to room temperature, the solid was removed by filtration. The filtrate was evaporated to dryness and the residue was purified by flash chromatography (silica gel, 45% dichloromethane/45% ethyl acetate/10% methanol) to give the title compound (0.066 g, 15%) MS(ES) m/z 203.8 [M+H].

Provenance & Evidence