反应详情

To 100% fuming nitric acid (10 mL) at −40° C. was added dropwise a solution of 3,3-dimethylbenzo[c][1,2]oxaborol-1(3H)-ol (XCVI) (1.37 g, 0.0085 mol) in carbon tetrachloride (40 mL), maintaining the temperature below −40° C. Stirring was continued for 20 min at −40° C. The yellow solution was poured onto ice and was stirred for 10 min at room temperature. The mixture was extracted with EtOAc. To the organic layer was added 1M aqueous NaOH to pH=7. The organic layer was separated, and washed with water, dried over MgSO4 and filtered, and the solvent was removed in vacuo to give an orange viscous oil. The oily residue was triturated with hexane to give pure 3,3-dimethyl-6-nitrobenzo[c][1,2]oxaborol-1(3H)-ol (XCVII) as a yellow solid (1.20 g, 5.8 mmol, yield 68%). 1H NMR (CDCl3) δ ppm 1.61 (s, 6H), 7.42 (s, 1H), 8.35 (d, J=8 Hz, 1H), 8.56 (d, J=8 Hz. 1H). ESIMS found for C9H10BNO4 m/z 206.3 (M−H).

1. temperaturemaintaining the temperature below −40° C
2. additionThe yellow solution was poured onto ice
3. stirringwas stirred for 10 min at room temperature
4. extractionThe mixture was extracted with EtOAc
5. additionTo the organic layer was added 1M aqueous NaOH to pH=7
6. customThe organic layer was separated
7. washwashed with water
8. dry with materialdried over MgSO4
9. filtrationfiltered
10. customthe solvent was removed in vacuo
11. customto give an orange viscous oil
12. customThe oily residue was triturated with hexane