Tetrafluoroboric acid → 3-Fluoro-5-hydroxy-4-methoxybenzoic acid

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Reaction Steps

The compound of step 1 (2.0 g, 8.88 mmol) was dissolved in aqueous tetrafluoroboric acid (48%, 4.5 ml), sodium nitrite (612 mg, 8.88 mmol) was added at 0° C., and the mixture was stirred at room temperature for 60 min. The volatiles were evaporated, toluene was added to the oily residue and the mixture was heated at 100° C. for 4 h. The mixture was partitioned between EA and 2 N hydrochloric acid, the aqueous phase extracted with EA, and the combined organic extracts were dried over sodium chloride, decanted and evaporated to dryness. The residue was purified by preparative RP HPLC (water/ACN gradient) to give 170 mg of the title compound.

Provenance & Evidence