[CH3:1][O:2][C:3]1[CH:8]=[CH:7][C:6]([C:9](=[O:12])[CH2:10][CH3:11])=[CH:5][CH:4]=1.[CH2:13](O)[CH2:14][OH:15]>C1(C)C=CC=CC=1.O.C1(C)C=CC(S(O)(=O)=O)=CC=1>[CH2:10]([C:9]1([C:6]2[CH:7]=[CH:8][C:3]([O:2][CH3:1])=[CH:4][CH:5]=2)[O:15][CH2:14][CH2:13][O:12]1)[CH3:11]To a solution of 4′-methoxypropiophenone (250.0 mg, 1.52 mmol) in toluene (20.0 mL) was added ethylene glycol (255.0 μL, 4.57 mmol) and p-toluenesulfonic acid monohydrate (13.0 mg, 0.04 mmol) and the reaction mixture refluxed overnight using a Dean-Stark apparatus. The reaction mixture was cooled to room temperature, then washed with saturated aqueous sodium bicarbonate solution followed by water. The toluene solution was then dried (MgSO4) and evaporated under reduced pressure to afford 2-ethyl-2-(4-methoxyphenyl)-1,3-dioxolane (16) as a yellow oil (184 mg, 58%). 1H nmr (CDCl3, 300 MHz) 0.76, t (6.6 Hz), CH3; 1.78, q (6.9 Hz), CH2; 3.65, m, CH2O, 3.73, s, 4′-OMe; 3.95, m, CH2O; 6.88, d (7.2 Hz), H3′,5′; 7.02, d, (7.5 Hz), H2′,6′. ESI (+ve) MS m/z 209 (M+H, 100%).
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