p-Toluenesulfonic acid → 2,2-dimethyl-3,4-dihydro-2H-1,3-benzoxazin-4-one

HRID 869887Notes

Reaction equation

HRID 869887 reaction equation
O[C:2]1[CH:3]=[C:4]([CH:8]=[CH:9][CH:10]=1)[C:5]([NH2:7])=[O:6].C[O:12][C:13](OC)([CH3:15])[CH3:14].C1(C)C=CC(S(O)(=O)=O)=CC=1>CC(C)=O>[CH3:14][C:13]1([CH3:15])[NH:7][C:5](=[O:6])[C:4]2[CH:3]=[CH:2][CH:10]=[CH:9][C:8]=2[O:12]1

Participants

5

Reactant 3

HCID 6101p-Toluenesulfonic acidHCID 64952,2-DimethoxypropaneHCID 3424033-Hydroxybenzamide

Product 1

HCID 7174282,2-dimethyl-3,4-dihydro-2H-1,3-benzoxazin-4-oneYield 86%

Reagents, catalysts & solvents 1

HCID 180AcetoneSolvent

Procedure

To a solution of 3-hydroxy-benzamide (50 g, 0.36 mol) in acetone (300 mL) was added 2,2-dimethoxy-propane (100 mL) and p-toluene sulfonic acid (5 g, 0.03 mol) and the mixture was heated to reflux overnight. The solvent was evaporated under vacuum to give crude 2,2-dimethyl-2H-benzo[e][1,3]oxazin-4(3H)-one (55 g, 86%) that was used in the next step without further purification. 1H NMR (300 MHz, CDCl3) δ 7.91 (dd, J=1.8, 7.8 Hz 1H), 7.44 (t, J=7.8 Hz 1H), 7.35 (brs, 1H), 7.05 (t, J=7.8 Hz 1H), 6.91 (d, J=8.1 Hz 1H), 1.65 (s, 6H).

Workup

  1. temperaturethe mixture was heated
  2. temperatureto reflux overnight
  3. customThe solvent was evaporated under vacuum

Sources & evidence

ORD record
ord-917336375f5f4dc0a90f70ef12ee5157
Source dataset
uspto-grants-2015_03
Patent number
US08969386B2

Reaction notes

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