ethyl (3R)-8-amino-9,10-difluoro-3-fluoromethyl-2,3-dihydro-7-oxo-7H-pyrido[1,2,3-de]-1,4-benzoxazine-6-carboxylate → (3R)-8-amino-9,10-difluoro-3-fluoromethyl-2,3-dihydro-7-oxo-7H-pyrido[1,2,3-de]-1,4-benzoxazine-6-carboxylic acid

Participants

Reaction Steps

A suspension of ethyl (3R)-8-amino-9,10-difluoro-3-fluoromethyl-2,3-dihydro-7-oxo-7H-pyrido[1,2,3-de]-1,4-benzoxazine-6-carboxylate (270 mg, 0.789 mmol) in a mixture of H2SO4—H2O—AcOH (1:5:6, 3 mL) was heated under reflux for 1 h. The reaction mixture was poured into ice-water and the resulting precipitates were collected by filtration. The filtered precipitates were washed with water, and dried in vacuo to give (3R)-8-amino-9,10-difluoro-3-fluoromethyl-2,3-dihydro-7-oxo-7H-pyrido[1,2,3-de]-1,4-benzoxazine-6-carboxylic acid (237 mg, 96%) as a yellow powder.

Provenance & Evidence