Methane, dichloromethoxy- → 3-Bromo-2-fluoro-4-methoxybenzaldehyde

In a 3-necked 250 mL round-bottomed flask equipped with nitrogen lines and a stir bar was placed 2-bromo-1-fluoro-3-methoxy-benzene (I-29, 2.0 g, 9.75 mmol) and dichloromethane (48 mL). The solution was cooled in an ice water bath for 15 minutes and then titanium tetrachloride (5.02 mL, 45.8 mmol) and dichloromethyl methyl ether (1.32 mL, 14.6 mmol) were added and the reaction mixture was allowed to warm to room temperature and react for 2 hours. The reaction mixture was slowly added to ice water (250 mL) and extracted with dichloromethane (2×100 mL). The organic portions were combined, washed with a saturated sodium bicarbonate solution (75 mL), water (75 mL) and brine (75 mL), dried (MgSO4) and concentrated. The crude material was triturated with hexanes (15 mL) to produce 1.67 g of 3-bromo-2-fluoro-4-methoxy-benzaldehyde (I-30) as an off-white solid in 74% yield. MS (ESI+): 233.2 (M+)