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温度

0 °C

A solution of 4-chloro-3-nitrobenzoic acid (10.03 g, 50 mmol), SOCl2 (4.4 mL, 60 mmol) and DMF (4 drops) in 1,2-dichloroethane (150 mL) was stirred under reflux for 14 h, cooled and evaporated. The resulting crude acid chloride was dissolved in THF (100 mL), cooled to 0° C., and a solution of potassium t-butoxide (5.57 g, 50 mmol) in THF (150 mL) was added dropwise over 30 min under nitrogen. The mixture was stirred a further 15 min at 0° C., diluted with aqueous NaHCO3 and extracted with EtOAc (×2), and the extracts were dried (Na2SO4) and evaporated. Flash chromatography of the residue on silica gel (petroleum ether/EtOAc; 30:1) gave t-butyl 4-chloro-3-nitrobenzoate as a white crystalline solid (11.45 g, 89%), mp (petroleum ether) 70-71° C. 1H NMR (CDCl3) d 8.42 (d, J=2.0 Hz, 1 H, H-2), 8.11 (dd, J=8.4, 2.0 Hz, 1 H, H-6), 7.61 (d, J=8.4 Hz, 1 H, H-5), 1.61 (s, 9 H, t-Bu). Anal. Calculated for C11H12ClNO4 : 51.3; H, 4.7; N, 5.4; Cl, 13.8. Found: C, 51.6; H, 4.8; N, 5.4; Cl, 14.0%.

1. temperatureunder reflux for 14 h
2. temperaturecooled
3. customevaporated
4. dissolutionThe resulting crude acid chloride was dissolved in THF (100 mL)
5. extractionextracted with EtOAc (×2)
6. dry with materialthe extracts were dried (Na2SO4)
7. customevaporated