实验操作如下 To a mixture of 6-chloro-5-nitro-2H-indazole (16; 160.0 kg, 810 mol) in EtOAc (2336 L, 14.6 vol)was added Me3O·BF4 (149.7 kg, 1012 mol) at 30 °C.
After stirring for 10 h, MeOH (379.4 kg, 3.0 vol)was added to the resulting mixture. The reaction mixture was mixed with 10% NaHCO3 aq., and theorganic layer was separated. The organic layer was washed with 6% NaCl aq., and then the organiclayer was separated off. The organic layer was mixed with activated carbon (80.1 kg, 0.5 wt) and THF(1120 L, 7.0 vol). After stirring for an adequate time, activated carbon was separated off. The filtratewas concentrated under reduced pressure, and then the amount of solution was adjusted to 8.3 wt withTHF. The solution was mixed with n-heptane (528.0 L, 3.3 vol) and stirred at 33°C, and then seedcrystal was added. n-Heptane (2912 L, 18.2 vol) was added again to the slurry at 33°C. Then theresulting slurry was cooled to − 8°C and filtered. The filtered solid was washed with a mixture of nheptane (436.8 L, 2.7 vol) and THF (107.2 L, 0.7 vol). The obtained solid was dried under reducedpressure at 50°C to afford 6-chloro-2-methyl-5-nitro-2H-indazole (17; 136.86 kg, 79.8%). 参考文献ACS Cent. Sci. 2023, 9, 836−843
