2-Fluoro-5-hydroxybenzaldehyde is solid at room temperature and pressure, with weak acidity and good chemical reaction activity, it is difficult to dissolve in water but can be dissolved in common organic solvents, including ethyl acetate, dichloromethane and so on.
2-Fluoro-5-hydroxybenzaldehyde is used in the enantioselective synthesis of 1,1''-spirobiindane-7,7''-diol (SPINOL) derivatives.
General procedure for the synthesis of 2-fluoro-5-hydroxybenzaldehyde from 2-fluoro-5-methoxybenzaldehyde:
Step 1: BBr3 (4 mL, 4 mmol, 1.0 M solution in heptane) was slowly added dropwise to a dichloromethane solution of 2-fluoro-5-methoxybenzaldehyde at -78 °C. The reaction mixture was stirred continuously at -78 °C for 1 hour, followed by slow warming to 0 °C and continued stirring for 2 hours. Upon completion of the reaction, the mixture was poured into water and extracted with ethyl acetate (3 x 10 mL). The organic phases were combined, washed sequentially with water and saturated brine and dried over anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure and the resulting residue was purified by silica gel column chromatography with 0-20% ethyl acetate-hexane mixed solvent as eluent, resulting in a white solid target product 2-fluoro-5-hydroxybenzaldehyde (142 mg, 25% yield). Mass spectrometry analysis showed m/z 141 [M + H]+.
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