The general procedure for the synthesis of 3-methyl-6-hydroxybenzisoxazole from the compound (CAS: 6134-79-8) was as follows: 2.0 mmol of 2-hydroxy aryl aldoxime or ketoxime was dissolved in 5 mL of anhydrous dichloromethane (DCM) in an oven-dried round-bottom flask. Under nitrogen protection, 2.0 mmol of DCM solution of trifluoromethanesulfonic anhydride was slowly added to the reaction mixture, and the titration process lasted for 15 minutes. The reaction mixture was stirred at room temperature and the reaction process was monitored by thin layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS) (see Table 1). Upon completion of the reaction, the reaction mixture was poured into 100 mL of crushed ice and neutralized with 20 mL of 10% sodium bicarbonate (NaHCO3) solution, followed by extraction with 315 mL of DCM. The pure product was isolated by column chromatography using hexane-ethyl acetate (80:20, v/v) as eluent. All the synthesized 1,2-benzisoxazole derivatives were characterized by GC-MS, nuclear magnetic resonance hydrogen spectroscopy (1H NMR) and carbon spectroscopy (13C NMR) as well as elemental analysis and the obtained data were validated by comparing them with real samples.
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