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

Beteiligte Stoffe

Reaktionsschritte

Oxalyl dichloride (21 mL, 221 mmol) and DMF (3 drops) were sequentially added to a solution of THF (300 mL) containing 2-(2,3-dimethylphenoxy)-2-methylpropanoic acid (38.3 g, 184 mmol) synthesized in Reference Example 16 under ice-cooling condition, and the mixture was warmed to room temperature and stirred for 1 hour. The reaction solution was concentrated under reduced pressure, and then the residue was dissolved in methylene chloride (250 mL). To this solution, aluminium chloride (36.2 g, 276 mmol) was added at −78° C., and the mixture was warmed to room temperature and stirred for 15 hours. The reaction solution was concentrated under reduced pressure, and then water was added to the residue and extraction was performed using ethyl acetate. The extract was washed with saturated saline, and then dried using anhydrous magnesium sulfate. The solvent was removed under reduced pressure, and the obtained residue was purified by silica gel chromatography (hexane-ethyl acetate 95:5 to 5/1) to give 26.4 g of the title compound (yield: 75%).

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