271-95-4

1. Synthesis of (E)-2-hydroxybenzaldehyde oxime: Triethylamine (190 mmol) was slowly added to a solution of 2-hydroxybenzaldehyde (164 mmol) and hydroxylamine hydrochloride (197 mmol) in ethanol (200 mL), and the reaction mixture was heated at 95 °C for 5 h. The reaction mixture was concentrated, and the residue was extracted with ethyl acetate (2 × 150 mL) and water (100 mL). The combined organic layers were washed with water (3 × 150 mL), dried (magnesium sulfate), and concentrated. The residue was purified by rapid chromatography (1/100 ethyl acetate/petroleum ether) to provide (E)-2-hydroxybenzaldehyde oxime as a white solid in 43% yield.

2) Synthesis of 1,2-BENZISOXAZOLE: At 0 °C, over 4 hours, a solution of DEAD (23.0 mmol) in tetrahydrofuran (150 mL) was added to a solution of (E)-2-hydroxybenzaldehyde oxime (21.9 mmol) and triphenylphosphine (23.0 mmol) in tetrahydrofuran (300 mL). The reaction mixture was then stirred at 0 °C for another 60 minutes and concentrated. The residue was purified by rapid chromatography (1/100 ethyl acetate/petroleum ether) to give 1,2-BENZISOXAZOLE as a yellow oil in 66% yield.