2,2-Dimethoxypropane → 5-Bromo-2,2-dimethylbenzo(d)(1,3)dioxole

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Reaction Steps

To benzene (50 mL) in a 250 mL round bottom flask was added 4-bromobenzene-1,2-diol (1 g, 5.29 mmol), 2,2-dimethoxypropane (2.204 g, 21.16 mmol), and p-toluene sulfonic acid monohydrate (0.050 g, 0.265 mmol). The flask was fitted with a Dean-Stark trap and heated to reflux for 18 h. Upon cooling, the reaction mixture was transferred to a separatory funnel and washed with 2 N NaOH solution (100 mL) and saturated NaCl solution (100 mL). The organic layer was dried with MgSO4, filtered, and concentrated to yield 5-bromo-2,2-dimethylbenzo[d][1,3]dioxole as a dark brown oil (767 mg, 63%): 1H NMR (400 MHz, CDCl3) δ 6.91-6.85 (m, 2H), 6.62-6.57 (m, 1H), 1.66 (s, 6H); 13C NMR (101 MHz, CDCl3) δ 146.81 (s), 144.25 (s), 123.64 (s), 121.02 (s), 112.05 (s), 109.40 (s), 108.46 (s), 25.83 (s); ESIMS m/z 230 ([M+H]+), 228 ([M−H]−).

Provenance & Evidence