Potassium Carbonate → ethyl 6-(trifluoromethyl)-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylate

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Reaction Steps

11.4 g of potassium carbonate was added to 48.7 g of 7B in 320 ml of acetone. Then 18.2 of ethyl 2,3-dibromopropionate was added dropwise to the refluxing mixture. This procedure was repeated thrice. The mixture was refluxed for 17 hours and filtered, and the filtrate was stripped of solvent under reduced pressure. The residue was dissolved in ether; the solution was washed with dilute sodium hydroxide solution, then dried (MgSO4) and stripped of solvent. The residue was washed with petroleum ether and dried. The residue was mixed with ether and filtered. Part of the solvent was evaporated from the filtrate; the remaining solution was cooled. Crystals which formed were filtered and recrystallized from ether to give 7, m.p.: 105°-107°.

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