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

HRID 641927Notes

Reaction equation

HRID 641927 reaction equation
[H-].[Al+3].[Li+].[H-].[H-].[H-].[O:7]1[CH2:12][C:11](=O)[NH:10][C:9]2[CH:14]=[CH:15][CH:16]=[CH:17][C:8]1=2>O1CCCC1>[O:7]1[CH2:12][CH2:11][NH:10][C:9]2[CH:14]=[CH:15][CH:16]=[CH:17][C:8]1=2

Participants

4

Reactant 2

HCID 727572H-1,4-benzoxazin-3(4H)-oneHCID 21226445Aluminium lithium hydride

Product 1

HCID 5850963,4-Dihydro-2H-1,4-benzoxazine

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent2×

Procedure

Into a 250 mL 3-necked round bottom flask was placed a solution of lithium aluminum hydride (3.6 g, 94.74 mmol) in tetrahydrofuran (80 ml). The mixture was stirred for 15 minutes. This was followed by the addition of a solution of 2H-benzo[b][1,4]oxazin-3(4H)-one (5.7 g, 38.22 mmol) in tetrahydrofuran (21 mL), which was added dropwise with stirring. The resulting solution was allowed to react, with stirring, overnight while the temperature was maintained at reflux in a bath of oil. The reaction progress was monitored by TLC (ethyl acetate/petroleum ether=1:1). The reaction mixture was then quenched by the adding 3.6 mL of H2O and 10.8 mL 15% NaOH. A filtration was performed. The filter cake was washed with 30 mL of tetrahydrofuran. The resulting solution was extracted two times with 100 mL of ethyl acetate and the organic layers combined and dried over Na2SO4 and concentrated by evaporation under vacuum using a rotary evaporator. This resulted in 4.8 g (79%) of 3,4-dihydro-2H-benzo[b][1,4]oxazine as red oil.

Workup

  1. customInto a 250 mL 3-necked round bottom flask was placed
  2. additionwas added dropwise
  3. stirringwith stirring
  4. customto react
  5. stirringwith stirring, overnight while the temperature
  6. temperaturewas maintained
  7. temperatureat reflux in a bath of oil
  8. customThe reaction mixture was then quenched by the adding 3.6 mL of H2O and 10.8 mL 15% NaOH
  9. filtrationA filtration
  10. washThe filter cake was washed with 30 mL of tetrahydrofuran
  11. extractionThe resulting solution was extracted two times with 100 mL of ethyl acetate
  12. dry with materialdried over Na2SO4
  13. concentrationconcentrated by evaporation under vacuum
  14. customa rotary evaporator
  15. customThis resulted in 4.8 g (79%) of 3,4-dihydro-2H-benzo[b][1,4]oxazine as red oil

Sources & evidence

ORD record
ord-60a2a91dc8f8441fb39f3050067be91c
Source dataset
uspto-grants-2010_04
Patent number
US07696229B2

Reaction notes

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