Synthesis
General procedure for the synthesis of 6-bromobenzo[d]oxazole from 2-amino-5-bromophenol and trimethyl orthoformate: A mixture of 2-amino-5-bromophenol (1.0 g, 5.34 mmol), p-toluenesulfonic acid (100 mg, 0.581 mmol), and trimethyl orthoformate (6 mL) was stirred and reacted for 1 hr at 80 °C and under nitrogen protection. After completion of the reaction, the mixture was concentrated under vacuum. The residue was purified by silica gel column chromatography (petroleum ether/ethyl acetate = 9:1) to afford 6-bromobenzo[d]oxazole (980 mg, 93% yield) as a brown solid.LC-MS analysis showed no specific mass peaks and retention time tR = 1.73 min.
