Pyridine → 3,5-Dichloro-1,2-benzoxazole

Participants

Reaction Steps

To a suspension of 5-chloro-3-hydroxy-1,2-benzisoxazole (100 g) in phosphorus oxychloride (80 ml) was added pyridine (48 ml) dropwise over 1 hours with stirring at room temperature, and the mixture was then refluxed for 5 hours. The reaction mixture was added to ice water (500 ml) and extracted with ethyl acetate and the combined extracts were dried over anhydrous magnesium sulphate. The solvent was evaporated under reduced pressure and the title compound (102 g, 92%) was obtained by recrystallizng the residue from petroleum ether as a colorless needle.

Provenance & Evidence