Phosphorus oxychloride → 2-Chloro-5-methyl-1,3-benzoxazole

Participants

Reaction Steps

To a suspension of 5-methylbenzo[d]oxazole-2-thiol (1.0 g, 6.1 mmol.) in POCl3 (11.7 g, 76.4 mmol.) at room temperature was added PCl5 (1.9 g, 9.15 mmol.) along with CH2Cl2 (10 mL). After 4 h of stirring at room temperature, the reaction mixture was concentrated to remove excess POCl3, and the residue was treated with Na2CO3 solution until ˜pH 8 was reached. The aqueous phase was extracted with CH2Cl2. The combined organic extracts were dried over Na2SO4, filtered and concentrated to afford 2-chloro-5-methylbenzo[d]oxazole (1.1 g crude product) which was used without further purification. MS (ESI) m/e (M+H+) 168.

Provenance & Evidence