Potassium Carbonate → (+/-)-Ethyl 2-ethoxy-3-[4-[2-[2,2dimethyl4-oxo-3,4-dihydro-1,3-benzoxazin-3-yl]ethoxy]phenyl]propanoate

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To a stirred solution of 2,2-dimethyl-4-oxo-3,4-dihydro-1,3-benzoxazine (0.3 g, 1.69 mmol) in DMF (3 mL) was added potassium carbonate (0.47 g, 3.39 mmol) and stirred for 30 min. To this reaction mixture was added a solution of ethyl 2-ethoxy-3-[4-(2-bromoethoxy) phenyl]propanoate (0.70 g, 2.03 mmol) (disclosed in U.S. patent application Ser. No. 09/012,585) in DMF (1 mL) and stirred for 24 h at 60-70° C. The reaction mixture was diluted with water and extracted with ethyl acetate (3×10 mL). The combined organic extracts were washed with brine, dried over anhydrous Na2SO4 and concentrated. The residue was chromatographed on silica gel using a gradient of 5-15% of ethyl acetate in pet ether as eluent to afford the title compound (0.34 g, 45%) as a liquid.

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