反应详情

To a mixture of 1-(5-hydroxy-2H-chromen-6yl)-propan-1-one (511 mg, 2.5 mmol) and (Rh(II)Ac2)2 (11 mg, 0.025 mmol) in 1,2-dichloroethane (8 mL) at 20° C., was added dropwise (3 h) a solution of ethyl diazoacetate (571 mg, 5 mmol) in 1,2-dichloroethane (2 mL). After 15 min at 20° C., the reaction mixture was washed with H2O (10 mL). The H2O phase was washed with CH2Cl2 (10 mL) and the solvent of the combined organic phases was removed under reduced pressure. The crude product was purified by column chromatography (silica gel, 1→5% MeOH in CH2Cl2), to give 300 mg (41%) of 7-hydroxy-6-propionyl-1,1a,2,7b-tetrahydro-cyclopropa[c]chromene-1-carboxylic acid ethyl ester (a 33/64 mixture of cis and trans isomers).

1. washthe reaction mixture was washed with H2O (10 mL)
2. washThe H2O phase was washed with CH2Cl2 (10 mL)
3. customthe solvent of the combined organic phases was removed under reduced pressure
4. customThe crude product was purified by column chromatography (silica gel, 1→5% MeOH in CH2Cl2)