Identification and Synthesis of Impurities in Pinocembrin A New Drug for the Treatment of Ischemic Stroke

Four minor impurities in pinocembrin （1）--a new drug to treat ischemic stroke, were analysed and identified by means of HPLC-UV-MS analysis, spectroscopic evidences and chemical synthetic methods. Their chemical struc- tures were identified as 5,7-dihydroxy-2-phenyl-4H-l-benzopyran-4-one （2）, 3-phenyl-l-（2,4,6-trihydroxyphenyl）- 1-propanone （3）, 5,%dihydroxy-2-cyclohexyl-4H-l-benzopyran-4-one （4）, and 2,3-dihydro-5,7-dihydroxy-2- cyclohexyl-4H-l-benzopyran-4-one （5）, respectively. All of the impurities were side products of excessive hydro- genation of the target product I or the starting material 2 in the course of synthesis, and 5 was a new compound.