Potassium Carbonate → 4-(4-cyclopropylethynyl-2-oxo-4-trifluoromethyl-1,4-dihydro-2H-benzo[d][1,3]oxazin-6-yloxy)-butyric Acid Ethyl Ester

Participants

Reaction Conditions

Reaction Steps

To 120 mg (0.40 mmol) of 9 were added 12 mL of anhydrous acetone, 120 mg (0.86 mmol) of anhydrous potassium carbonate, 2 mg of 18-crown-6 and 40 μL (0.28 mmol) of ethyl 4-bromobutyrate. The reaction mixture was allowed to stir at 56° C. for 3 hours and was concentrated under reduced pressure. To the residue 20 mL of water were added followed by 1 mL of 1N HCl. The aqueous layer was extracted with 4×20 mL of dichloromethane. The organic layers were combined, dried (Na2SO4), and concentrated under reduced pressure. The residue was purified by preparative thin layer chromatography (silica gel, 2 mm thickness, E. Merck) using 1% methanol in dichloromethane to give 45 mg (0.11 mmol, 27%) of 10 as a colorless thick oil [LC-MS; M+H 412.1].

Provenance & Evidence