反应详情

4.93 g (11.5 mmol) of the (Z) diester obtained in Example 17 (step D) are dissolved in 100 ml of methylene chloride which has been passed over basic alumina. The solution is irradiated for 2.5 h using a Hanovia TQ 150 lamp after having added dropwise 1.53 ml of boron trifluoride etherate solution (11.5 mmol). The solution is then washed with 1N hydrochloric acid solution (twice 80 ml), with saturated sodium hydrogen carbonate solution (twice 80 ml) and is dried over magnesium sulphate. After filtration and evaporation, 2.56 g of (E) isomer are recovered after flash chromatography.

1. customThe solution is irradiated for 2.5 h
2. washThe solution is then washed with 1N hydrochloric acid solution (twice 80 ml), with saturated sodium hydrogen carbonate solution (twice 80 ml)
3. dry with materialis dried over magnesium sulphate
4. filtrationAfter filtration and evaporation, 2.56 g of (E) isomer
5. customare recovered after flash chromatography