9-epi-ent-7,15-isopimaradiene derivatives from Calceolaria glandulosa

Abstract In addition to two new 9- epi -pimarane diterpenes, the aerial parts of Calceolaria glandulosa yielded a new bis-diterpene, glandulosate, derived from the esterification of malonic acid by two 18-hydroxy- ent -9- epi -7,15-isopimaradiene units. The structures of the compounds were elucidated by spectroscopic evidence and chemical transformations.