Acetonitrile--water (1/1) → HCID 57457165, compound

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Reaction Steps

Ethyl 4-{2-[(1,1-dimethylethyl)oxy]-2-oxoethyl}-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-6-carboxylate (6.14 g, 18.0 mmol) was dissolved in 60 mL of a 1:1 solution of methylene chloride and trifluoroacetic acid. The mixture was allowed to stir at room temperature for three hours before it was determined to be complete by HPLC (Eclipse XDB-C18, 4.6×250 mm, 5 micron, 1-99% CH3CN/H2O with 0.1% trifluoroacetic acid). The chromatogram indicated that all of the starting material (Rt=7.7 min) was consumed and converted to the desired product (Rt=5.3 min). The volatiles were removed by rotary evaporation and the resulting residue was taken up in a minimal amount of methylene chloride and treated with a 2 M solution of hydrochloric acid in ethyl ether. After allowing the mixture to stir for several minutes, the mixture was concentrated once again by rotary evaporation to yield {6-[(ethyloxy)carbonyl]-3-oxo-2,3-dihydro-4H-1,4-benzoxazin-4-yl}acetic acid (5.28 g, 17.9 mmol, 99%) as a brown amorphous solid. MS (ES) m/e 280 [M+H]+.

Provenance & Evidence