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General procedure for the synthesis of 3-(benzyloxy)isoxazole-5-carbaldehyde from (3-(benzyloxy)isoxazol-5-yl)methanol: (3-(benzyloxy)isoxazol-5-yl)methanol (0.45 g, 2.19 mmol) was dissolved in dichloromethane and solid pyridinium dichromate (PDC, 1.24 g, 3.3 mmol) was added. The reaction mixture was stirred at room temperature for 16 h. Upon completion of the reaction, it was filtered through diatomaceous earth and eluted with dichloromethane (3 x 75 mL). The organic layers were combined and washed sequentially with 1 M aqueous HCl (2 × 50 mL) and 10% aqueous NaCl (100 mL), and the organic phase was dried with anhydrous Na2SO4, filtered, and concentrated under reduced pressure to give a brown oil. The crude product was purified by silica gel column chromatography with gradient elution of hexane/ethyl acetate (95/5 to 70/30) to afford 3-(benzyloxy)isoxazole-5-carbaldehyde as a brown solid (0.3 g, 67% yield).

[1] Organic Process Research and Development, 2015, vol. 19, # 11, p. 1784 - 1795
[2] Patent: WO2012/87833, 2012, A1. Location in patent: Page/Page column 133