(S)-2-ethyl-7-methoxycarbonyl-4-(2-propyl)-3-oxo-3,4-dihydro-2H-1,4-benzoxazine → (S)-2-ethyl-4-(2-propyl)-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-7-carboxylic acid

Participants

Reaction Steps

A mixture of (S)-2-ethyl-7-methoxycarbonyl-4-(2-propyl)-3-oxo-3,4-dihydro-2H-1,4-benzoxazine (0.85 g) in concentrated hydrochloric acid (20 ml) was stirred under reflux for a day. The concentrated hydrochloric acid was distilled off under reduced pressure. Water was added to the residue and extraction with ethyl acetate was conducted. The extract was washed with water and then the solvent was distilled off under reduced pressure to give (S)-2-ethyl-4-(2-propyl)-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-7-carboxylic acid (0.70 g).

Provenance & Evidence