Sodium Carbonate → 1-(6-Amino-2,3-dihydro-4H-1,4-benzoxazin-4-yl)ethan-1-one

To a solution of the crude 1-(6-nitro-2H-benzo[b][1,4]oxazin-4(3H)-yl)ethanone (0.86 g, 3.89 mmol) in EtOAc (8 mL) was added SnCl2.2H2O (4.3834 g, 19.4 mmol) and the mixture was heated under reflux with stirring. After 1.5 h, the mixture was cooled to rt. To the mixture was added 2 M aqueous Na2CO3 (20 mL) followed by EtOAc (50 mL). The resulting white precipitate was filtered off and washed the white solid with EtOAc (50 mL). The filtrated was separated in a reparatory funnel. The aqueous layer was extracted with EtOAc (30 mL×1). The combined organics were washed with brine (50 mL×2), dried over Na2SO4, filtered, and concentrated under reduced pressure to give dark syrup. The dark syrup was purified by column chromatography on a silica gel column using 0 to 100% gradient of DCM-MeOH—NH4OH (89:9:1) in DCM as eluent to give 1-(6-amino-2H-benzo[b][1,4]oxazin-4(3H)-yl)ethanone as a red syrup: Mass Spectrum (ESI) m/e=193.1 (M+1).

1. temperaturethe mixture was heated
2. temperatureunder reflux
3. filtrationThe resulting white precipitate was filtered off
4. washwashed the white solid with EtOAc (50 mL)
5. customThe filtrated was separated in a reparatory funnel
6. extractionThe aqueous layer was extracted with EtOAc (30 mL×1)
7. washThe combined organics were washed with brine (50 mL×2)
8. dry with materialdried over Na2SO4
9. filtrationfiltered
10. concentrationconcentrated under reduced pressure
11. customto give dark syrup
12. customThe dark syrup was purified by column chromatography on a silica gel column

ORD record

ord-ed617fc5d37d44ec8cb71bcc6ce9063f

Source dataset

uspto-grants-2014_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08765940B2