Sodium Hydroxide → 5-Phenyl-4,5-dihydro-1,2-oxazole-3-carboxylic acid

Temperature

45 °C

To a solution of 4,5-dihydro-N,N-dimethyl-5-phenyl-3-isoxazolecarboxamide (i.e. the product of Example 12, Step A) (60.0 g, 275 mmol) in methanol (300 mL) was added an aqueous sodium hydroxide solution (44 g of 50 wt. % aqueous NaOH in 50 mL of water) dropwise over 30 minutes while maintaining the temperature of the reaction mixture at 45° C. The reaction mixture was allowed to cool to room temperature and stirred overnight. The resulting mixture was concentrated under reduced pressure and treated with 200 mL of water. The pH of the reaction mixture was adjusted using concentrated hydrochloric acid to about 1.0. The crude product was extracted into ethyl acetate (200 mL). The ethyl acetate solution was concentrated under reduced pressure, and the residue was triturated with hexanes. The resulting precipitate was filtered, washed with hexanes (2×20 mL), and dried under vacuum to give 46.5 g of the title compound as a solid.

1. temperatureto cool to room temperature
2. concentrationThe resulting mixture was concentrated under reduced pressure
3. additiontreated with 200 mL of water
4. extractionThe crude product was extracted into ethyl acetate (200 mL)
5. concentrationThe ethyl acetate solution was concentrated under reduced pressure
6. customthe residue was triturated with hexanes
7. filtrationThe resulting precipitate was filtered
8. washwashed with hexanes (2×20 mL)
9. customdried under vacuum

ORD record

ord-2d1fa3992f374862b7a530faffb2e37b

Source dataset

uspto-grants-2013_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08449898B2