Hydrochloric Acid → 5-[4-[5-(2,6-difluorophenyl)-4,5-dihydro-3-isoxazolyl]-2-thiazolyl]tetrahydro-2H-1,2-oxazine

Participants

Reaction Steps

A solution of ethyl 5-[4-[5-(2,6-difluorophenyl)-4,5-dihydro-3-isoxazolyl]-2-thiazolyl]tetrahydro-2H-1,2-oxazine-2-carboxylate (i.e. the product of Step J) (0.30 g, 0.71 mmol) and potassium hydroxide (0.20 g, 3.50 mmol) in ethanol (10 mL) and water (1 mL) was heated at reflux for 20 h, and then cooled to room temperature. The reaction mixture was acidified by the addition of concentrated hydrochloric acid, heated at 70° C. for about 20 minutes, cooled to room temperature, and then basified by the addition of sodium hydroxide (1%). The reaction mixture was extracted with ethyl acetate (20 mL) and combined organic extracts were concentrated under reduced pressure to provide the title compound as a yellow oil (0.235 g) which was used without purification.

Provenance & Evidence