反应详情

To a slurry of 5.3 g. (110 mmol) of 50% NaH in mineral oil in 425 ml. of dry DMF, stirred at 3° under argon, was added portionwise over a 20 minute time period, 20.26 g. (110 mmol) of 3,5-pyrazole dicarboxylic acid dimethyl ester*, maintaining a temperature of 5°-8°. When the vigorous hydrogen evolution had stopped, the ice bath was removed and the reaction allowed to warm to room temperature while stirring for 20 minutes. A solution of 24.5 g. (110 mmol) of 2-fluoro-5-nitrobenzophenone, in 100 ml. of dry DMF was added dropwise over 40 minutes and when addition was complete, the reaction was heated at 65° for 1.5 hr. After cooling, the mixture was poured over a mixture of ice and brine and extracted well with a 1:1 EtOAc:ether mixture. The combined extracts were washed with brine, dried over MgSO4 and concentrated. The crude mixture was chromatographed on silica gel using as an eluent benzene mixed with 0-100% EtOAc. The residue remaining after the solvents were evaporated was recrystallized from EtOAc/hexane to give the final product. The analytical sample was prepared by an additional recrystallization from EtOAc/hexane and was obtained as off-white needles: mp 150°-152°.

1. additionwas added portionwise over a 20 minute time period, 20.26 g
2. customthe ice bath was removed
3. additionwhen addition
4. temperaturethe reaction was heated at 65° for 1.5 hr
5. temperatureAfter cooling
6. extractionextracted well with a 1:1 EtOAc
7. washThe combined extracts were washed with brine
8. dry with materialdried over MgSO4
9. concentrationconcentrated
10. customThe crude mixture was chromatographed on silica gel using as an eluent benzene
11. additionmixed with 0-100% EtOAc
12. customwere evaporated
13. customwas recrystallized from EtOAc/hexane