Preparation process and structure confirmation of impurity C of rupatifen fumarate

The high-purity impurity C was isolated and purified from a new anti-allergic drug, rupatifen, by nucleophilic substitution reaction with bromobutaric acid, and its structure was confirmed by IR, UV, MS, ¹H NMR, ¹³C NMR, DEPT135°,HSQC, HMBC, and ¹H-¹HCOSY. The preparation process of impurity C in this study was simple and easy to obtain under mild conditions, with the purity of 99.0% and the yield of 25%-30%;and the sample met the target compound by structural confirmation. The preparation process and structure confirmation provided sufficient impurity C reference substance for impurity research of raw materials and preparations of rupatifen fumarate, which laid a solid foundation for quality research of new drugs.