(5-Bromo-2-methylfuran-3-yl)methanol → 5-Bromo-2-methylfuran-3-carbaldehyde

A solution of methyl 5-bromo-2-methyl-3-furancarboxylate (Example 49 (1)) (7.5 g) in tetrahydrofuran (30 mL) was added dropwise to a suspension of lithium aluminum hydride (1.9 g) in tetrahydrofuran (30 mL) at 0° C. and, after the completion of the dropwise addition, the mixture was stirred at 0° C. for 30 min. The reaction mixture was treated with 1N hydrochloric acid, poured into water, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine, and dried over magnesium sulfate. The solvent was evaporated under reduced pressure, and the residue was purified by silica gel chromatography (5% ethyl acetate/hexane to 40% ethyl acetate/hexane) to give (5-bromo-2-methylfuran-3-yl)methanol (5.7 g, 60%) as an oil. A suspension of the obtained (5-bromo-2-methylfuran-3-yl)methanol (5.5 g) and manganese dioxide (15 g) in tetrahydrofuran (100 mL) was stirred at 40° C. for 2 days. Manganese dioxide was filtered off, and the filtrate was evaporated under reduced pressure. The residue was purified by silica gel chromatography (0% ethyl acetate/hexane to 20% ethyl acetate/hexane), and crystallized from ethyl acetate/hexane to give the title compound (2.8 g, 51%) as a white solid.