Fig. 2
From: A synthesis strategy for tetracyclic terpenoids leads to agonists of ERβ
Design of a synthesis strategy to access varied tetracyclic terpenoid skeletons. a Examples of steroid hormones including an estrane, an androstane, and a pregnane. b Complex tetracyclic terpenoids that present distinct challenges for chemical synthesis in comparison with relatively simple steroid hormones. c Design of a concise approach to the enantiospecific assembly of C19 tetracyclic terpenoid core skeletons 5 and 6
