METHODS Silica gel G was used as stationary phase and a mixture of 1,2-dichloroethane and diethyl ether (80:20) was used as mobile phase.

• 方法使用硅胶G薄层板，以1,2-二氯乙烷-乙醚(80:20)为展开剂，5%25香草醛硫酸溶液为显色剂。