16263-54-0

General procedure for the synthesis of 3,6-dichlorobenzo[d]isoxazole from 6-chlorobenzo[d]isoxazol-3-ol: 6-chlorobenzo[d]isoxazol-3-ol (6 g, 35 mmol), phosphorochloridic acid chloride (20 ml) and triethylamine (1 ml) were added to a microwave reactor. The reaction was carried out at 150°C for 0.5 h. The phosphorus trichloride was subsequently removed by evaporation. The residue was diluted with dichloromethane (20 ml) and added to an ice-water mixture (20 g). After stirring the mixture, the organic phase was separated. The aqueous phase was extracted with dichloromethane (20 ml x 2), the organic layers were combined, washed with saturated brine (20 ml) and dried over anhydrous magnesium sulfate. After evaporation of the solvent, it was purified by chromatography on an alumina column (200-300 mesh) with dichloromethane:methanol=200:1 as eluent to give 3,6-dichlorobenzo[d]isoxazole (5.2 g, 79% yield).

[1] Patent: EP2322520, 2011, A1. Location in patent: Page/Page column 12
[2] Patent: JP5714152, 2015, B2. Location in patent: Paragraph 0068; 0071
[3] Chemische Berichte, 1967, vol. 100, # 10, p. 3326 - 3330