Preparation method of two high-purity clevidipine butyrate impurities

The invention relates to a preparation method of two clevidipine butyrate impurities of 4-(2, 4-dichlorophenyl)-1, 4-dihydro-2, 6-dimethyl-3, 5-pyridine dicarboxylic acid methyl ester butyryloxy methyl ester (I) and 4-(3, 4-dichlorophenyl)-1, 4-dihydro-2, 6-dimethyl-3, 5-pyridine dicarboxylic acid methyl ester butyryloxy methyl ester (II). Through preparation of the clevidipine butyrate impurities, an impurity reference substance is provided for quality research of clevidipine butyrate. I:R1=Cl, R2=H; II:R1=H, R2=Cl. 本发明涉及两种丁酸氯维地平杂质4-(2,4-二氯苯基)-1,4-二氢-2,6-二甲基-3,5-吡啶二羧酸甲酯丁酰氧基甲酯(I)和4-(3,4-二氯苯基)-1,4-二氢-2,6-二甲基-3,5-吡啶二羧酸甲酯丁酰氧基甲酯(II)的制备方法。通过对丁酸氯维地平杂质的制备，为丁酸氯维地平的质量研究提供杂质对照品。I：R1＝Cl，R2＝H；II：R1＝H，R2＝Cl。