beta-Chloroethyl acetate → 2-Chloro-3-[2-methyl-4-(5,6,7,8-tetrahydronaphthalen-2-yl)-5-oxazolyl]propionic acid

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Reaction Steps

To a solution of [2-methyl-4-(5,6,7,8-tetrahydronaphthalen-2-yl)-5-oxazolyl]methanol (3.3 g) in (40 mL) was added thionyl chloride (1.5 mL) at 0° C. After stirring at room temperature for 15 min, the reaction mixture was concentrated. To the residue was added saturated aqueous sodium hydrogen carbonate, and the mixture was extracted with ethyl acetate. The organic layer was washed successively with water and saturated brine, dried over anhydrous magnesium sulfate, and concentrated to give an oil. To a mixed solution of 2-chloroethyl acetate (2.68 g) and N,N-dimethylformamide (40 mL) was added sodium hydride (60% in oil, 0.6 g) and the mixture was stirred at 0° C. for 5 min. To this the reaction mixture was added a solution of the aforementioned oil in N,N-dimethylformamide (10 mL) at room temperature and the mixture was stirred at room temperature for 2.5 hrs. Water was poured into the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed successively with water and saturated brine, dried over anhydrous magnesium sulfate and concentrated. The residue was diluted with ethanol (30 mL) and a 2N aqueous sodium hydroxide solution (16 mL) was added at 0° C. and the mixture was stirred for 20 min. Water was added to the reaction mixture and the mixture was washed with diethyl ether. The aqueous layer was acidified with 2N aqueous hydrochloric acid solution, and the mixture was extracted with ethyl acetate. The organic layer was washed successively with water and saturated brine, dried over anhydrous magnesium sulfate and concentrated. The precipitated crystals were collected by filtration and recrystallized from ethanol to give 2-chloro-3-[2-methyl-4-(5,6,7,8-tetrahydronaphthalen-2-yl)-5-oxazolyl]propionic acid (3.93 g, yield 91%) as colorless prism crystals. melting point: 141–142° C.

Provenance & Evidence