反应详情

10.0 g (47.7 mmol) of the compound from Example 8A and 8.3 g (57.1 mmol) of the compound from Example 11A are initially charged in 100 ml of ethanol, and 1.5 ml (2.2 g, 19.0 mmol) of trifluoroacetic acid are added. The mixture is stirred under reflux for 12 h. An excess of a 4 M solution of hydrogen chloride in dioxane is then added to the cooled reaction mixture, the mixture is stirred for about 1 h, the precipitated crystals are filtered off and the filter residue is washed with dioxane and ethanol. The intermediate obtained in this manner is dissolved in 150 ml of ethanol, 50 ml of a 25% strength methanolic sodium methoxide solution are added and the mixture is stirred at RT for 2 h. The reaction mixture is then adjusted with 1 N hydrochloric acid to pH=5 and stirred at RT for a further 2 h, the solid is filtered off, the filter residue is washed with ethanol and the product is dried under reduced pressure. Yield: 7.0 g (49% of theory)

1. temperatureunder reflux for 12 h
2. stirringthe mixture is stirred for about 1 h
3. filtrationthe precipitated crystals are filtered off
4. washthe filter residue is washed with dioxane and ethanol
5. customThe intermediate obtained in this manner
6. stirringthe mixture is stirred at RT for 2 h
7. stirringstirred at RT for a further 2 h
8. filtrationthe solid is filtered off
9. washthe filter residue is washed with ethanol
10. customthe product is dried under reduced pressure