Acetone → 2,2-dimethyl-3,4-dihydro-2H-1,3-benzoxazin-4-one

HRID 842972Notes

Reaction equation

HRID 842972 reaction equation
[C:1]([NH2:10])(=[O:9])[C:2]1[C:3](=[CH:5][CH:6]=[CH:7][CH:8]=1)[OH:4].[CH3:11][C:12]([CH3:14])=O>S(=O)(=O)(O)O>[CH3:11][C:12]1([CH3:14])[NH:10][C:1](=[O:9])[C:2]2[CH:8]=[CH:7][CH:6]=[CH:5][C:3]=2[O:4]1

Participants

4

Reactant 2

HCID 180AcetoneHCID 5147Salicylamide

Product 1

HCID 7174282,2-dimethyl-3,4-dihydro-2H-1,3-benzoxazin-4-oneYield 47%

Reagents, catalysts & solvents 1

HCID 1118Sulfuric AcidCatalyst

Procedure

A solution of salicylamide (4.14 g, 30.2 mmol) and conc. sulfuric acid (3 drops) in acetone (40 mL) was refluxed for 5 h. The reaction was concentrated and the residue taken up in ethyl acetate. The organic solution was washed with 1 N NaOH (2×), 1 N HCl (2×), H2O, then sat. aq. NaCl, dried (MgSO4) and concentrated to afford 2,2-dimethyl-4-keto-1,3-benzoxazine (2.50 g, 47%) as a white solid: 1H NMR (CDCl3, 300 MHz, ppm) 7.92 (d, 1H), 7.60 (bs, 1H), 7.47 (m, 1H), 7.06 (m, 1H), 6.92 (d, 1H), 1.65 (s, 6H).

Workup

  1. concentrationThe reaction was concentrated
  2. washThe organic solution was washed with 1 N NaOH (2×), 1 N HCl (2×), H2O
  3. dry with materialsat. aq. NaCl, dried (MgSO4)
  4. concentrationconcentrated

Sources & evidence

ORD record
ord-496ff65bb88641c6b98bbf3a44c448a9
Source dataset
uspto-grants-2002_04
Patent number
US06376538B1

Reaction notes

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