[CH3:1][O:2][CH2:3][C:4]([C:9]1[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=1)([CH3:8])[CH2:5][CH:6]=C.CSC.CC1C=CC(S(O)(=O)=[O:26])=CC=1>CO.ClCCl.CC(C)=O.C(=O)(O)[O-].[Na+]>[CH3:1][O:2][CH2:3][C:4]([CH3:8])([C:9]1[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=1)[CH2:5][CH:6]=[O:26]
To a chilled (−78° C.) solution of (1-methoxymethyl-1-methylbut-3-enyl)benzene (1.67 g, 8.77 mmol) in methanol-dichloromethane was bubbled ozone gas until the solution turned blue. The excess ozone was then purged from the mixture with oxygen and then dimethyl sulfide (5 mL, 68 mmol) was added and the mixture was warmed to room temperature and stirred overnight. The mixture was then concentrated in vacuo to remove the excess dimethyl sulfide and diluted with 20 mL of ammonium chloride and extracted with three 15 mL portions of ethyl acetate. The combined organic layers were washed with three 15 mL portions of brine, dried over magnesium sulfate, filtered, and concentrated in vacuo to afford an oil which corresponded to the dimethyl acetal by 1H-NMR. The crude product was diluted with 40 mL of acetone and p-TsOH (300 mg, 1.57 mmol) was added and the mixture was stirred at room temperature for 2 hours. The reaction was monitored by 1H-NMR and indicated the presence of aldehyde and dimethyl acetal. The reaction was refluxed for 4 hours and monitored by TLC (ethyl acetate-hexanes (1:9)) and then cooled and diluted with saturated aqueous sodium bicarbonate solution and extracted with three 15 mL portions of ethyl acetate. The combined organic layers were washed with two 10 mL portions of saturated aqueous sodium bicarbonate solution, two 10 mL portions of brine, dried over magnesium sulfate, filtered, and concentrated in vacuo to afford 1.45 g (85.9% yield) of 4-methoxy-3-methyl-3-phenylbutyraldehyde.
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