p-Toluenesulfonic acid → Ethyl 2,2-dimethylbenzo[d][1,3]dioxole-5-carboxylate

HRID 1453433Notes

Reaction equation

HRID 1453433 reaction equation
[OH:1][C:2]1[CH:3]=[C:4]([CH:10]=[CH:11][C:12]=1[OH:13])[C:5]([O:7][CH2:8][CH3:9])=[O:6].CO[C:16](OC)([CH3:18])[CH3:17].C1(C)C=CC(S(O)(=O)=O)=CC=1>C1(C)C=CC=CC=1>[CH3:17][C:16]1([CH3:18])[O:13][C:12]2[CH:11]=[CH:10][C:4]([C:5]([O:7][CH2:8][CH3:9])=[O:6])=[CH:3][C:2]=2[O:1]1

Participants

5

Reactant 3

HCID 6101p-Toluenesulfonic acidHCID 64952,2-DimethoxypropaneHCID 77547Ethyl 3,4-Dihydroxybenzoate

Product 1

HCID 66773240Ethyl 2,2-dimethylbenzo[d][1,3]dioxole-5-carboxylateYield 49%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

Ethyl 3,4-dihydroxybenzoate (910.9 mg, 5 mmol) was combined with 2,2-dimethoxypropane (1.23 mL, 10 mmol) and a catalytic amount of p-toluene sulfonic acid in toluene. The mixture was heated to reflux using a Dean-Stark trap for 20 hours. After solvent removal under reduced pressure, the crude was dissolved in ethyl acetate and washed successively with a saturated aqueous solution of sodium bicarbonate, water, and brine. The organic layer was dried over anhydrous sodium sulfate. Purification by chromatography on silica gel using a gradient hexane:ethyl acetate, 90:10 to 75:25, afforded a white powder (539.1 mg, 49%). 1H NMR(CDCl3): δ 1.36 (t, 3H, J=7.2 Hz), 1.69 (s, 6H), 4.32 (q, 2H, J=7.1 Hz, J=14.2 Hz), 6.74 (d, 1H, d, J=8.2 Hz), 7.38 (d, 1 h, J=1.7 Hz), 7.61 (dd, 1H, J=1.8 Hz, J=8.3 Hz).

Workup

  1. temperatureThe mixture was heated
  2. temperatureto reflux
  3. customfor 20 hours
  4. customAfter solvent removal under reduced pressure
  5. dissolutionthe crude was dissolved in ethyl acetate
  6. washwashed successively with a saturated aqueous solution of sodium bicarbonate, water, and brine
  7. dry with materialThe organic layer was dried over anhydrous sodium sulfate
  8. customPurification by chromatography on silica gel using a gradient hexane

Sources & evidence

ORD record
ord-b6df6e067b9542df9f9f0aba8ef8c7e2
Source dataset
uspto-grants-2009_01
Patent number
US07476399B2

Reaction notes

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