[C:1]([O:5][C:6]([C:8]1[S:9][C:10]([CH:13]=O)=[CH:11][CH:12]=1)=[O:7])([CH3:4])([CH3:3])[CH3:2].CCOP([O:23][C:24]([CH3:26])=[O:25])(OCC)=O.[H-].[Na+].O1CC[CH2:31][CH2:30]1>>[C:1]([O:5][C:6]([C:8]1[S:9][C:10]([CH:13]=[CH:26][C:24]([O:23][CH2:30][CH3:31])=[O:25])=[CH:11][CH:12]=1)=[O:7])([CH3:2])([CH3:3])[CH3:4]1.7 g (8 mmol) of the product obtained in step c) were dissolved in 5 ml of dry tetrahydrofuran. The solution was added dropwise to a mixture of 2.24 g (10 mmol) of diethyl phosphonoacetate and 440 mg sodium hydride (55% in paraffin oil) in 30 ml of dry tetrahydrofuran. The resulting mixture was stirred at 60° C. for 3 hours. After cooling to room temperature, the mixture was poured onto water/ethyl acetate. The organic phase was separated, washed with 10% aqueous citric acid and dried with anhydrous magnesium sulfate. After filtration, the solvents were removed to give 2.6 g of raw product. This material was purified by column chromatography (silica gel; ethyl acetate/n-heptane (1/5; v/v)). The fractions containing the title compound were combined and evaporated to give 1.2 g of a clear light yellow oil.
Wird geladen…
