Hydrochloric Acid → 2-t-Butyldimethylsilyl-3-formyl-6-methoxy-7-isopropoxybenzofuran

HRID 2059626Notes

Reaction equation

HRID 2059626 reaction equation
[Si:1]([CH:8]1[C:12](=[CH:13][O:14][Si](C(C)(C)C)(C)C)[C:11]2[CH:22]=[CH:23][C:24]([O:30][CH3:31])=[C:25]([O:26][CH:27]([CH3:29])[CH3:28])[C:10]=2[O:9]1)([C:4]([CH3:7])([CH3:6])[CH3:5])([CH3:3])[CH3:2].Cl>CO>[Si:1]([C:8]1[O:9][C:10]2[C:25]([O:26][CH:27]([CH3:28])[CH3:29])=[C:24]([O:30][CH3:31])[CH:23]=[CH:22][C:11]=2[C:12]=1[CH:13]=[O:14])([C:4]([CH3:6])([CH3:7])[CH3:5])([CH3:2])[CH3:3]

Participants

4

Reactant 2

HCID 313Hydrochloric AcidHCID 670422652-t-Butyldimethylsilyl-3-(t-butyldimethylsilyloxymethylene)-6-methoxy-7-isopropoxybenzofuran

Product 1

HCID 574219592-t-Butyldimethylsilyl-3-formyl-6-methoxy-7-isopropoxybenzofuran

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Procedure

To a solution of 2-t-butyldimethylsilyl-3-(t-butyldimethylsilyloxymethylene)-6-methoxy-7-isopropoxy-benzofuran (2.69 mmol) in methanol (100 mL) was added concentrated hydrochloric acid (200 μL) and the reaction was stirred for 30 minutes (tlc), quenched with triethylamine (2 mL) and the solvent removed by distillation under vacuum. The residue was dissolved in dichloromethane (20 mL), washed with water (10 mL), dried over magnesium sulphate, concentrated under vacuum and co-distilled with toluene (20 mL). The crude product was dissolved in dry dichloromethane (4 mL) and added to a stirred solution of Collin's reagent [chromium trioxide (1.01 g), pyridine(1.65 mL) in dry dichloromethane (30 mL)]. The suspension was stirred for 10 minutes, filtered and the residue washed with diethyl ether (20 mL). The filtrate was concentrated onto silica (10 g) and purified by flash chromatography (silica gel, eluent=hexane/diethyl-ether/triethylamine (90:9:1) to afford the title compound as a light yellow oil; (503 mg, 48%); 1H NMR (300 MHz, CDCl3) δ 10.25(s, 1H, CHO), 7.79(d, 1H, J=8.45 Hz), 6.98(d, 1H, J=8.46 Hz), 4.65(m, 1H), 3.89(s, 3H, OMe), 1.35(d, 6H, J=6.17 Hz), 0.97 (s, 9H), 0.45(s, 6H).

Workup

  1. customquenched with triethylamine (2 mL)
  2. customthe solvent removed by distillation under vacuum
  3. dissolutionThe residue was dissolved in dichloromethane (20 mL)
  4. washwashed with water (10 mL)
  5. dry with materialdried over magnesium sulphate
  6. concentrationconcentrated under vacuum and co-distilled with toluene (20 mL)
  7. dissolutionThe crude product was dissolved in dry dichloromethane (4 mL)
  8. additionadded to a stirred solution of Collin's reagent [chromium trioxide (1.01 g), pyridine(1.65 mL) in dry dichloromethane (30 mL)]
  9. stirringThe suspension was stirred for 10 minutes
  10. filtrationfiltered
  11. washthe residue washed with diethyl ether (20 mL)
  12. concentrationThe filtrate was concentrated onto silica (10 g)
  13. custompurified by flash chromatography (silica gel, eluent=hexane/diethyl-ether/triethylamine (90:9:1)

Sources & evidence

ORD record
ord-7bdd9621f0d041e8a2aa8317f8409bd5
Source dataset
uspto-grants-2012_10
Patent number
US08278290B2

Reaction notes

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