Hydrochloric Acid → 6-nitro-3,4-dihydro-2H-1,4-benzoxazine

Temperature

75 °C

To a suspension of 6-nitro-2H-benzo[b][1,4]oxazin-3(4H)-one (1.45 g, 7.47 mmol) in THF (11 mL) was added BH3.THF (1 M solution in THF, 60 mL) at rt and the mixture was stirred at 75° C. After 3.5 h, the mixture was cooled to rt. To the cooled mixture was added MeOH (30 mL) and mixture was stirred at rt. After 30 minutes, the mixture was treated with concentrated HCl (6 mL, 72 mmol) and concentrated under reduced pressure. The residue was dissolved in EtOAc (50 mL×4), washed with brine (100 mL×2), dried over Na2SO4, filtered, and concentrated under reduced pressure. The residue was purified by column chromatography on a silica gel column using 0 to 100% gradient of EtOAc in hexane as eluent to give 6-nitro-3,4-dihydro-2H-benzo[b][1,4]oxazine as a reddish-orange solid: Mass Spectrum (ESI) m/e=181.0 (M+1).

1. temperaturethe mixture was cooled to rt
2. stirringwas stirred at rt
3. waitAfter 30 minutes
4. concentrationconcentrated under reduced pressure
5. dissolutionThe residue was dissolved in EtOAc (50 mL×4)
6. washwashed with brine (100 mL×2)
7. dry with materialdried over Na2SO4
8. filtrationfiltered
9. concentrationconcentrated under reduced pressure
10. customThe residue was purified by column chromatography on a silica gel column

ORD record

ord-d4d1de1539954c1eb245cf0cd21e2e77

Source dataset

uspto-grants-2014_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08765940B2