Trifluoroacetic acid → HCID 57457149, compound

Participants

Reaction Steps

Several smaller batches of ethyl 3-oxo-3,4-dihydro-2H-1,4-benzoxazine-6-carboxylate were combined. A solution of ethyl 3-oxo-3,4-dihydro-2H-1,4-benzoxazine-6-carboxylate (4.1 g, 19.0 mmol) dissolved in 30 mL of anhydrous tetrahydrofuran was added drop-wise to a mixture of sodium hydride (60% by weight in mineral oil, 0.8 g, 20 mmol) suspended in 60 mL of anhydrous tetrahydrofuran under argon. The mixture was allowed to stir at room temperature for 10 minutes before t-butyl-2-bromoacetate (3.4 mL, 23 mmol) was added to the mixture and stirred vigorously for 2 hours. HPLC (Eclipse XDB-C18, 4.6×250 mm, 5 micron, 1-99% CH3CN/H2O with 0.1% trifluoroacetic acid) chromatogram indicated that all of the starting material (Rt=5.5 min) was consumed and only a single new product had formed (Rt=7.7 min). The reaction was quenched by adding 8 mL of a 4 M solution of hydrochloric acid in dioxane. After allowing the mixture to stir for one hour, all of the volatiles were removed by rotary evaporation to give 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, 96%). MS (ES) m/e 280 [M−t-butyl C4H9]+.

Provenance & Evidence