反应详情

38.0 g (244.9 mmol) of the compound from Example 3A are stirred in 126 ml (108.1 g, 734.7 mmol) of N,N-dimethylformamide diethyl acetal at a bath temperature of 90° C. for 16 h. After cooling, the mixture is concentrated under reduced pressure, the residue is stirred with diisopropyl ether and the solid is filtered off and finally washed with diisopropyl ether. Yield: 49.0 g (95% of theory)

1. temperatureAfter cooling
2. concentrationthe mixture is concentrated under reduced pressure
3. filtrationthe solid is filtered off
4. washfinally washed with diisopropyl ether