Diethyl Ether → Benzothiazole

A solution of 4-Bromomethyl benzothiazole (20.4 g, 89.9 mmol) in 272 mL of dry DMF was treated with NaN3 (7.00 g, 108 mmol) at 20° C. and stirred at the same temperature for 5 min. The resulting mixture was quenched by addition of NaCl (5 g in 150 mL of H2O) at 0° C., diluted with Et2O (200 mL) and extracted with Et2O (200 mL×6). The organic phase was washed with NaCl (2 g in 100 mL of H2O) twice and brine (100 mL). The resulting solution was dried over MgSO4 and concentrated in vacuo. The residue was submitted to silica gel column chromatography with toluene:Et2O=50:3 to 50:5 as eluate to afford 4-azidemethyl benzothiazole as a colorless oil (15.5 g, 81.5 mmol, 91%). Rf=0.48 (toluene:Et2O=10:1); 1H NMR (400 MHz, CDCl3) δ 9.03 (1H, s), 7.95 (1H, d, J=7.7 Hz), 7.49 (2H, m), 5.01 (2H, s); 13C NMR (99.5 MHz, CDCl3) δ 154.2, 151.7, 134.3, 130.6, 126.0, 125.7, 122.1, 51.6.