[CH3:1][C:2]1[CH:10]=[CH:9][C:5]2[O:6][CH2:7][O:8][C:4]=2[CH:3]=1.C=O.Cl[CH2:14][Cl:15].Cl>[Br-].C([N+](CCCC)(CCCC)CCCC)CCC.CCOCC>[Cl:15][CH2:14][C:10]1[C:2]([CH3:1])=[CH:3][C:4]2[O:8][CH2:7][O:6][C:5]=2[CH:9]=1
At about 0° C., 5-methylbenzo[d][1,3]dioxole (500 mg, 3.68 mmol) and formaldehyde (37% in water, 0.7 mL) were sequentially added to a mixture of dichloromethane (6.8 mL), tetrabutylammonium bromide (80 mg) and concentrated hydrochloric acid (6.5 mL). Under continuous stirring, the mixture was maintained at about 0° C. for about 1 hour and then at ambient temperature for about 4 hours. The mixture was diluted with ether (100 mL). After standard extractive workup, the resulting solid residue was heated with hexanes (100 mL) and the insolubles were removed by filtration. The filtrate was concentrated to give desired product (420 mg, 62%). 1H NMR (300 MHz, CDCl3) δ 6.89 (s, 1H), 6.69 (s, 1H), 5.94 (s, 3H), 4.56 (s, 2H), 2.35 (s, 3H); GC-MS: m/z=184 (MH)+.
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