Methanol → 7-Nitro-3,4-dihydro-2H-1,4-benzoxazine

HRID 424468Notes

Reaction equation

HRID 424468 reaction equation
[N+:1]([C:4]1[CH:5]=[CH:6][C:7]2[NH:12][C:11](=O)[CH2:10][O:9][C:8]=2[CH:14]=1)([O-:3])=[O:2].B.C1COCC1.CO>C1COCC1>[N+:1]([C:4]1[CH:5]=[CH:6][C:7]2[NH:12][CH2:11][CH2:10][O:9][C:8]=2[CH:14]=1)([O-:3])=[O:2]

Participants

5

Reactant 3

HCID 887MethanolHCID 2723981Borane;tetrahydrofuranHCID 27638307-nitro-3,4-dihydro-2H-1,4-benzoxazin-3-one

Product 1

HCID 184161517-Nitro-3,4-dihydro-2H-1,4-benzoxazine

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

A suspension of 7-nitro-2H-benzo[b][1,4]oxazin-3(4H)-one (300 mg, 1.545 mmol) in THF (3 mL) was treated with BH3-THF complex (15.45 mL, 15.45 mmol, 1.0 M in THF), and the resulting orange solution was refluxed overnight. The reaction was cooled in an ice-bath. MeOH (15 mL) was added, and the reaction was then concentrated. A second portion of MeOH (20 mL) was added, and the solution was refluxed for 2 hours. At this time, the reaction was concentrated, and the residue was subjected to flash chromatography on silica gel (10% EtOAc:90% hexane followed by 30% EtOAc:70% hexane). An orange solid was obtained after drying under reduced pressure. (240 mg, 86%). 1H-NMR (DMSO-d6) δ 7.68 (dd, J=2.4, 8.9 Hz, 1H), 7.54 (s, 1H), 7.47 (d, J=2.4 Hz, 1H), 6.63 (d, J=9.0 Hz, 1H), 4.15 (t, J=4.2 Hz, 2H), 3.45-3.40 (m, 2H).

Workup

  1. temperaturethe resulting orange solution was refluxed overnight
  2. temperatureThe reaction was cooled in an ice-bath
  3. concentrationthe reaction was then concentrated
  4. additionA second portion of MeOH (20 mL) was added
  5. temperaturethe solution was refluxed for 2 hours
  6. concentrationAt this time, the reaction was concentrated
  7. customAn orange solid was obtained
  8. customafter drying under reduced pressure

Sources & evidence

ORD record
ord-d873901d51594884bb45bbbd13309274
Source dataset
uspto-grants-2012_01
Patent number
US08106043B2

Reaction notes

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