The present invention relates to a novel process for preparing (4S)-4-(4-cyano-2-methoxyphenyl)-5-ethoxy-2,8-dimethyl-1,4-dihydro-1,6-naphthyridine-3-carboxamide of the formula (I) and recovering (4S)-4-(4-cyano-2-methoxyphenyl)-5-ethoxy-2,8-dimethyl-1,4-dihydro-1,6-naphthyridine-3-carboxamide of the formula (I)
proceeding from (4R)-4-(4-cyano-2-methoxyphenyl)-5-ethoxy-2,8-dimethyl-1,4-dihydro-1,6-naphthyridine-3-carboxamide of the formula ent-(I)
本发明涉及一种制备(4S)-4-(4-
氰基-2-
甲氧基苯基)-5-乙氧基-2,8-二甲基-1,4-二氢-1,6-
萘啶-3-羧酰胺(式(I))并从(4R)-4-(4-
氰基-2-
甲氧基苯基)-5-乙氧基-2,8-二甲基-1,4-二氢-1,6-
萘啶-3-羧酰胺ent-(I)的方法中回收(4S)-4-(4-
氰基-2-
甲氧基苯基)-5-乙氧基-2,8-二甲基-1,4-二氢-1,6-
萘啶-3-羧酰胺(式(I))的新工艺。