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

HRID 25145

Reaction equation

HRID 25145 reaction equation
[N+:1]([C:4]1[CH:5]=[CH:6][C:7]2[O:12][CH2:11][C:10](=O)[NH:9][C:8]=2[CH:14]=1)([O-:3])=[O:2].CO>O1CCCC1>[N+:1]([C:4]1[CH:5]=[CH:6][C:7]2[O:12][CH2:11][CH2:10][NH:9][C:8]=2[CH:14]=1)([O-:3])=[O:2]

Participants

4

Reactant 2

HCID 887Methanol2×HCID 27636836-Nitro-2H-1,4-benzoxazin-3(4H)-one

Product 1

HCID 70622256-nitro-3,4-dihydro-2H-1,4-benzoxazine

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent2×

Procedure

To a suspension of 6-nitro-4-H-benzo[1,4]oxazin-3-one (7.84 g, 40.38 mmol) in tetrahydrofuran (100 mL) was added a solution of 2.0M borane-methyl sulfide complex in tetrahydrofuran (91 mL, 181 mmol). The mixture was heated to reflux for 4.5 hours then allowed to stir overnight at room temperature. Methanol was added slowly to react with unreacted borane-methyl sulfide complex, which resulted a violent evolution of gas. When this subsided, excess methanol was added and the solution heated to reflux. After 2 hours the solution was cooled, the solvent evaporated under vacuum, and the residue triturated with ethyl acetate/hexane. An orange solid was filtered off which was rinsed with hexane, to yield 6-nitro-3,4-dihydro-2H-benzo[1,4]oxazine as a solid product. More of the solid was recovered as a second crop from the filtrate.

Workup

  1. temperatureThe mixture was heated
  2. temperatureto reflux for 4.5 hours
  3. customto react with unreacted borane-methyl sulfide complex, which
  4. customresulted a violent evolution of gas
  5. temperaturethe solution heated to reflux
  6. temperatureAfter 2 hours the solution was cooled
  7. customthe solvent evaporated under vacuum
  8. customthe residue triturated with ethyl acetate/hexane
  9. filtrationAn orange solid was filtered off which
  10. washwas rinsed with hexane

Sources & evidence

ORD record
ord-67d4f4c14c9d4d6ca9700aa849fccfb8
Source dataset
uspto-grants-2005_02
Patent number
US06858621B2

Linked notes

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