Boron tribromide → 2,4,4-trimethyl-4H-3,1-benzoxazin-5-ol

HRID 527660Notes

Reaction equation

HRID 527660 reaction equation
C[O:2][C:3]1[C:8]2[C:9]([CH3:15])([CH3:14])[O:10][C:11]([CH3:13])=[N:12][C:7]=2[CH:6]=[CH:5][CH:4]=1.B(Br)(Br)Br>C(Cl)Cl>[CH3:13][C:11]1[O:10][C:9]([CH3:14])([CH3:15])[C:8]2=[C:3]([OH:2])[CH:4]=[CH:5][CH:6]=[C:7]2[N:12]=1

Participants

4

Reactant 2

HCID 25134Boron tribromide2×HCID 679601135-Methoxy-2,4,4-trimethyl-4H-3,1-benzoxazine2×

Product 1

HCID 679601202,4,4-trimethyl-4H-3,1-benzoxazin-5-olYield 103.3%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent3×

Procedure

5-Methoxy-2,4,4-trimethyl-4H-3,1-benzoxazine (Intermediate 201, 342 mg, 1.67 mmol) was dissolved in DCM (7 mL) and 1M BBr3 solution in DCM (1.67 ml, 1.67 mmol) was added. After 1.5 h at room temperature the mixture was heated to reflux and after 6 hours at reflux, some more 1M BBr3 solution in DCM (1.67 ml, 1.67 mmol) was added leaving the mixture at reflux overnight. The reaction mixture was quenched with an aqueous saturated solution of NaHCO3 while the pH was allowed to become basic. Two phases were separated and the organic layer was washed with brine, dried over Na2SO4 and evaporated to dryness, to obtain the title compound (330 mg) as foam.

Workup

  1. temperatureto reflux and after 6 hours
  2. temperatureat reflux
  3. customleaving the mixture
  4. temperatureat reflux overnight
  5. customThe reaction mixture was quenched with an aqueous saturated solution of NaHCO3 while the pH
  6. customTwo phases were separated
  7. washthe organic layer was washed with brine
  8. dry with materialdried over Na2SO4
  9. customevaporated to dryness

Sources & evidence

ORD record
ord-3c17571969ef40939c66bbc99e36f2cb
Source dataset
uspto-grants-2016_05
Patent number
US09346790B2

Reaction notes

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