Procedure for the synthesis of 5-fluoro-2-methylbenzoxazole: 2-amino-4-fluorophenol (1.01 g, 7.95 mmol, 1.0 eq.), triethyl orthoacetate (1.60 mL, 8.7 mmol, 1.1 eq.), and bismuth(III) trifluoromethanesulfonate (50 mg) were mixed and stirred for 30 min at room temperature. Upon completion of the reaction, the reaction mixture was diluted with dichloromethane and purified by rapid chromatography on silica gel (eluent: dichloromethane) to afford 5-fluoro-2-methylbenzoxazole as a clear liquid in a yield of 1.045 g (87% yield). The liquid could be converted to a crystalline solid at lower than 5 °C. Mass spectrum (MALDI-TOF): MH+ = 152. UV/Vis spectrum (methanol): maximum absorption wavelength λmax = 282, 276, 230 nm. 1H NMR (400 MHz, CDCl3): δ 2.60 (s, 3H), 7.02 (1H, td), 7.33 (1H, dd), 7.39 (1H, dd).
