Diisobutylaluminumhydride → 5-Bromo-6-methylpicolinaldehyde

A 250 mL round-bottom flask was purged with and maintained under an inert atmosphere of nitrogen then charged with methyl 5-bromo-6-methylpyridine-2-carboxylate (7.00 g, 30.6 mmol, 1.00 equiv), tetrahydrofuran (150 mL). Diisobutylaluminium hydride (60 mL, 1 mol/L in hexane) was added dropwise at −78° C. The resulting solution was stirred for 60 min at −78° C., quenched by ammonium chloride (50 mL), extracted with ethyl acetate (2×100 mL). The organic layers were combined, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was chromatographed on a silica gel column with ethyl acetate/petroleum ether (10/90) to provide 4.90 g (76% yield) of 5-bromo-6-methylpyridine-2-carbaldehyde as a light yellow solid. 1H NMR 300 MHz (CDCl3) δ 10.04 (s, 1H), 8.02 (d, J=8.1 Hz, 1H), 7.67 (d, J=8.4 Hz, 1H), 2.78 (s, 3H). LCMS (ESI, m/z): 200 [M+H]+.