反应详情

温度

60 °C

Aqueous sodium hydroxide solution (50% w/v, 1.63 mL) was added slowly to a vigorously stirred mixture of methyl 7-methoxymethyl-2H-chromene-8-carboxylate (Intermediate 9, 0.875 g), benzyltriethylammonium chloride (0.173 g) and bromoform (15 mL). The resultant mixture was vigorously stirred and heated at 60° C. for 3 hours. After cooling, the mixture was poured into a mixture of brine and ethyl acetate. The aqueous layer was further extracted with ethyl acetate and the combined organic layers were dried (MgSO4) and filtered. The filtrate was evaporated to dryness and the residue was purified by chromatography on silica, eluting with a mixture of TBME and cyclohexane with a gradient of 0-35% to give methyl cis-(1aRS,7bSR)-1,1-dibromo-5-methoxymethyl-1,1a,2,7b-tetrahydrocyclopropa[c]chromene-4-carboxylate (1.06 g) as a white solid.

1. temperatureAfter cooling
2. extractionThe aqueous layer was further extracted with ethyl acetate
3. dry with materialthe combined organic layers were dried (MgSO4)
4. filtrationfiltered
5. customThe filtrate was evaporated to dryness
6. customthe residue was purified by chromatography on silica
7. washeluting with a mixture of TBME and cyclohexane with a gradient of 0-35%