2 EUDESMANOLIDE-TYPE SESQUITERPENE LACTONES FROM UMBELLIFERAE

(1) 1-beta-Angeloyloxy-2-beta,3-beta-epoxy-5-beta-H,7-alpha-H-10-alpha-methyleudesma-4(15),11(13)-dien-6,12-olide; (II) 1-beta-angeloyloxy-5-beta-H,6-alpha-H,7-alpha-H,11-alpha-H-10-alpha-methyl-eudesma-2,4(15)-dien-6,12-olide. (I) and (II) are two closely related native eudesmanolides whose structures are based on the fundamental 5-beta-H,6-alpha-H,-7-alpha-H,10-alpha-CH3-eudesman-6,12-olide skeleton. As regards molecular conformation, the largest difference between the two compounds is in the cyclohexane B ring which is of the rigid chair type in (I) and of the flexible boat type in (II).