反应详情

1,1′-carbonyldiimidazole (1.99 g, 12.30 mmol) was added to a solution of the 3-(benzyloxy)-6-methyl-4-oxo-4H-pyran-2-carboxylic acid (2.0 g, 7.69 mmol) in dimethylformamide (DMF, 18 ml) at room temperature. The resulting solution was heated at 40°-50° C. for 3 hrs. A light yellow solution was observed. Cyclohexylamine (1.23 ml, 10.76 mmol) was then added. The resulting mixture was stirred at room temperature for overnight. The DMF was removed under reduced pressure to give light yellow oil as a crude product, which was purified by flash column chromatography (elution gradient: from 1:1 ethyl acetate/hexane to 10% methanol in ethyl acetate) to yield the titled compound (1.60 g, yield 61%) as white solid.

1. temperatureThe resulting solution was heated at 40°-50° C. for 3 hrs
2. customThe DMF was removed under reduced pressure
3. customto give light yellow oil as a crude product, which
4. customwas purified by flash column chromatography (elution gradient: from 1:1 ethyl acetate/hexane to 10% methanol in ethyl acetate)