2-(4-Chloro-benzylidene)-3-methyl-succinic acid → 6-Chloro-4-hydroxy-3-methyl-naphthalene-2-carboxylic acid

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Reaction Steps

To a flask containing trifluoromethanesulfonic acid (40 mL), 2-(4-chloro-benzylidene)-3-methyl-succinic acid (14.0 g) was added in portions. After being stirred at room temperature for 18 hours, the resulting mixture was poured onto ice-water, and stirred for 15 minutes. The formed precipitate was collected by filtration, and dissolved in ethyl acetate (150 mL). The solution was dried over sodium sulfate, and concentrated in vacuo. The residue was precipitated from ethyl acetate/petroleum ether (1:10) to afford 6-chloro-4-hydroxy-3-methyl-naphthalene-2-carboxylic acid (12.7 g, 97.6%) as a pink solid.

Provenance & Evidence