Abstract
Studies on the structures of alisol B, alisol B monoacetate and alisol C monoacetate, the new biological-active triterpenes of Alismatis Rhizoma, are reported. The former two compounds have been correlated to alisol A (1) establishing their structures as shown 2 and 4, respectively. The structure of alisol C monoacetate has been clarified to be 16-oxoalisol B 23-monoacetate (21) on the basis of correlation of the compound with 4. Stereochemical courses and mechanisms of some epoxide cleavage reactions of 2, 4 and alisol B diacetate (8) are also described.
