Dihydrobenzofuran → 4-(2,3-Dihydrobenzofuran-7-yl)-2-hydroxy-4-methyl-2-trifluoromethylpentanoic acid ethyl ester

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Reaction Steps

A solution of 2-hydroxy-4-methyl-2-trifluoromethylpent-4-enoic acid ethyl ester (100 g, 442 mmol) and 2,3-dihydrobenzofuran (57.7 g, 480 mmol) in 500 mL of dichloroethane was treated with AlCl3 (87.8 g, 660 mmol) while maintaining the internal temperature below 10° C. The reaction was allowed to warm to room temperature overnight and quenched with 1 L of cold 1 N HCl. The mixture was then extracted with three 1 L portions of ethyl acetate. The combined organic layers were washed with 1 L of saturated aqueous sodium bicarbonate solution, 1 L of brine, dried over magnesium sulfate, filtered, and concentrated in vacuo. The residue was purified on SiO2 (10% diethyl ether in hexanes). The resulting solid was recrystallized from hot hexanes to afford 39.5 g of 4-(2,3-dihydrobenzofuran-7-yl)-2-hydroxy-4-methyl-2-trifluoromethylpentanoic acid ethyl ester as a white solid (26%).

Provenance & Evidence