21725-69-9

ChEBI: Benzo[d]isoxazol-3-ol is a benzisoxazole.

The general procedure for the synthesis of benzo[D]isoxazol-3-ol from salicylhydroxamic acid is as follows: intermediate 1 (1.92 M in THF solution) was placed in a reaction vial and stirred at 60 °C. CDI (3.84 M, THF solution) was added slowly over 30 minutes. The reaction mixture was heated to reflux and reflux was continued at 60 °C for 2 hours. Upon completion of the reaction, the mixture was cooled to 40 °C and subsequently evaporated to remove the solvent. The residue was quenched with water and the pH was adjusted to 2 with 12 N HCl. The mixture was stirred for 30 min followed by filtration at 10-15 °C to collect the precipitate. The precipitate was washed with ice water and finally dried under reduced pressure at 90 °C to give 3-hydroxybenzisoxazole (Intermediate 2) in quantitative yield.

[1] Patent: WO2005/89753, 2005, A2. Location in patent: Page/Page column 27
[2] Tetrahedron Letters, 2016, vol. 57, # 48, p. 5301 - 5303
[3] Tetrahedron: Asymmetry, 1995, vol. 6, # 2, p. 321 - 324
[4] Bulletin of the Chemical Society of Japan, 1983, vol. 56, # 8, p. 2485 - 2489