2-Aminophenol → 2H-1,4-benzoxazin-3(4H)-one

A solution of chloroacetyl chloride (31.2 g) in chloroform (100 ml) was added dropwise to a mixture of 2-aminophenol (25 g), benzylmethylammonium chloride (52.4 g), sodium bicarbonate (77 g) and chloroform (500 ml) which was cooled in an ice-bath. The mixture was stirred for 1 hour and allowed to warm to ambient temperature. The mixture was heated to 55° C. for 5 hours and then stirred at ambient temperature for 16 hours. The mixture was evaporated and the residue was partitioned between ethyl acetate and an aqueous solution of potassium carbonate. The organic phase was washed with dilute aqueous hydrochloric acid and with water, dried (MgSO4) and evaporated. The residue was washed with a mixture of hexane and diethyl ether to leave 3-oxo-2,3-dihydro-4H-1,4-benzoxazine (11 g, 32%) m.p. 172°-173° C.

1. temperaturewas cooled in an ice-bath
2. temperatureThe mixture was heated to 55° C. for 5 hours
3. stirringstirred at ambient temperature for 16 hours
4. customThe mixture was evaporated
5. customthe residue was partitioned between ethyl acetate
6. washThe organic phase was washed with dilute aqueous hydrochloric acid and with water
7. dry with materialdried (MgSO4)
8. customevaporated
9. washThe residue was washed with a mixture of hexane and diethyl ether

ORD record

ord-996fe16b080848a784e403139ecb531b

Source dataset

uspto-grants-1994_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05373007