Dimethylformamide → 2,2,6,7-Tetramethyl-1-benzofuran-3(2H)-one

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Reaction Steps

To a solution of 2-(2,3-dimethylphenoxy)-2-methylpropionic acid obtained in Reference Example 36 (21.0 g, 101 mmol) in THF (200 mL) was added DMF (0.1 mL), and then to the mixture was added dropwise oxalyl chloride (10.6 mL, 121 mmol). The reaction solution was warmed to room temperature, stirred for 1 hour, and then concentrated under reduced pressure. The residue was dissolved in dichloromethane (200 mL), to which was added aluminum chloride (32.3 g, 242 mmol) at −70° C. or lower, and then warmed to room temperature over 12 hours. The reaction solution was added to water with ice-cooling and dichloromethane was distilled off under reduced pressure, which was extracted with ethyl acetate. The organic layer was washed with water, a saturated sodium hydrogen carbonate solution, water and a saturated brine, and then was dried over anhydrous sodium sulfate. The residue after distilling off the solvent under reduced pressure was crystallized from ethyl acetate-hexane to obtain 17.5 g (yield 71%) of the title compound. Melting point: 79-81° C. (methanol).

Provenance & Evidence