Purification of 2-methoxyethyl 1-methylethyl 2,6-dimethyl-4-(3-nitrophenyl)pyridine-3,5-dicarboxylate by preparative high-performance liquid chromatography

The 2-methoxyethyl 1-methylethyl 2,6-dimethyl-4-(3-nitrophenyl)pyridine-3,5 -dicarboxylate was obtained in a 99.8% pure form from raw material by prepa rative-scale high performance liquid chromatography. This compound is an im purity in the industrial process of nimodipine. The chromatographic conditi ons were optimized to achieve any efficient purification in the shortest ti me. A reversed-phase preparative-scale HPLC column was used. This work demo nstrates how gram quantities of pure material can be conveniently obtained using preparative HPLC, even when the components in a mixture are difficult to reserve.