反应详情

温度

0 °C

Hünig's base (0.5 mL, 2.86 mmol) was added to a solution of 1,1-dimethylethyl 4-[(4-fluoro-2-hydroxy-5-methylphenyl)amino]-1-piperidinecarboxylate (D1, 593 mg, 1.34 mmol) in dichloromethane (10 mL) at rt under argon. The reaction was cooled to 0° C. and the triphosgene (167 mg, 0.564 mmol) was added. The reaction was then stirred for 1.5 h at 0° C. and quenched with saturated aqueous NaHCO3 (10 mL) before being partitioned between dichloromethane and water. The aqueous layer was extracted with dichloromethane (2×) and the combined organics were dried (Na2SO4) and concentrated by rotary evaporation to give an orange oil. The residue was purified via chromatography (silica, dichloromethane to 0.5% ammonia/9.5% methanol/90% dichloromethane) to give 1,1-dimethylethyl 4-(6-fluoro-5-methyl-2-oxo-1,3-benzoxazol-3(2H)-yl)-1-piperidine carboxylate (D2, 546 mg, 73% purity, 85% yield) as an orange oil.

1. customquenched with saturated aqueous NaHCO3 (10 mL)
2. custombefore being partitioned between dichloromethane and water
3. extractionThe aqueous layer was extracted with dichloromethane (2×)
4. dry with materialthe combined organics were dried (Na2SO4)
5. concentrationconcentrated by rotary evaporation
6. customto give an orange oil
7. customThe residue was purified via chromatography (silica, dichloromethane to 0.5% ammonia/9.5% methanol/90% dichloromethane)