The importance of the sesquiterpene lactone thapsigargin as a tool for studying Ca2+ homeostasis has created a need for structure-activity relationship studies and consequently for procedures for selective transformations of the functional groups in the molecule. Methods for the selective inversion of configuration at C-3 and C-8, selective acetylation, and selective cleavage of the ester groups at 0-3, 0-8 and 0-10 are presented.