153403-53-3

145096-57-7

153403-53-3

The general procedure for the synthesis of 2-chloro-6-fluorobenzoxazole from 6-fluorobenzo[d]oxazole-2(3H)-thione was as follows: to a 500 mL round-bottomed flask was added 6-fluoro-2,3-dihydro-1,3-benzoxazole-2-thione (9.2 g, 54.38 mmol, 1.00 equiv.), thionyl chloride (200 mL) and N,N-dimethylformamide ( DMF, 0.5 mL). The reaction mixture was stirred in an oil bath at 80 °C for 6 hours. Upon completion of the reaction, the excess thionyl chloride was removed by distillation under reduced pressure. The residue was purified by silica gel column chromatography with ethyl acetate/petroleum ether (0/100 to 7/93) as eluent. The fraction containing the target product was collected and concentrated under reduced pressure to give 3.5 g (38% yield) of 2-chloro-6-fluorobenzoxazole as a brown oil. The product was confirmed by LC-MS (electrospray ionization, m/z) with a molecular ion peak [M+H]+ of 172.