反应详情

A stirred mixture of concentrated sulphuric acid (98%, 270 ml) and fuming nitric acid (270 ml) at 0° C. was treated portionwise with Example 1 (90 g, 530 mmol). Upon complete dissolution, stirring was continued at room temperature for a further 20 min. The solution was added slowly to vigorously stirred ice/water (2000 ml). After 30 min stirring at room temperature, a yellow solid was filtered, washed with water and dried in vacuo at 40° C. to give the title compound in 61% yield, >95% purity. LC-MS m/z=251.0 [M+H]+; RT=2.92; LC-MS method 1. 1H NMR: δH (400 MHz, D6-DMSO) 7.66 (1H, s), 11.71 (1H, b), 11.79 (1H, b).

1. dissolutionUpon complete dissolution
2. stirringAfter 30 min stirring at room temperature
3. filtrationa yellow solid was filtered
4. washwashed with water
5. customdried in vacuo at 40° C.