反应详情

To a stirred solution of 780 mg (3.51 mmol) (4-methoxy-benzooxazol-2-yl)-carbamic acid methyl ester in 40 ml nitromethane at 0° C. was added 699 mg (5.27 mmol) nitronium tetrafluoroborate and stirring continued for 18 h while the reaction mixture was allowed to warm gradually to room temperature. The mixture was then concentrated in vacuo. Flash chromatography (ethyl acetate/hexane) afforded 300 mg (32%) (4-methoxy-5-nitro-benzooxazol-2-yl)-carbamic acid methyl ester as an orange solid, and 220 mg (32%) (4-methoxy-7-nitro-benzooxazol-2-yl)-carbamic acid methyl ester as a yellow solid. ES-MS m/e (%): 268 (M+H+, 100).

1. concentrationThe mixture was then concentrated in vacuo