The general procedure for the synthesis of 5-bromomethyl-2,3-dihydro-1,4-benzodioxole from (2,3-dihydrobenzo[b][1,4]dioxin-5-yl)methanol was as follows: (2,3-dihydrobenzo[b][1,4]dioxin-5-yl)methanol (3.75 g, 32.3 mmol) was dissolved in ethyl ether (80 mL) and the solution was cooled to 0 °C. Phosphorus tribromide (3.67 mL, 38.8 mmol) was added slowly and dropwise with stirring. The reaction mixture was continued to be stirred at 0 °C for 10 minutes, then brought to room temperature and stirred for 1 hour. Upon completion of the reaction, water (10 mL) was carefully added to quench the excess phosphorus tribromide. The mixture was diluted with ether and washed with water (3 x 50 mL). The combined organic layers were washed with brine (100 mL), dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to afford 5-bromomethyl-2,3-dihydro-1,4-benzodioxole as a brown solid (4.61 g, 62% yield). The product was characterized by 1H NMR (CDCl3): δ 6.91-6.77 (m, 3H), 4.52 (s, 2H), 4.35-4.33 (m, 2H), 4.29-4.27 (m, 2H). Mass spectrum measured value: [M + H-Br] = 149.5.
