From Homer to hedgehog: Cyclopamine, the first inhibitor of the hedgehog signaling pathway, causes cyclopia in embryos but in adults it is a potent anticancer drug. A concise biomimetic and diastereoselectivesynthesis of cyclopamine (2) starting from commercially available dehydroepiandrosterone (1) now also provides access to several analogues.
The chemical synthesis and biologicalevaluation of new cyclopamine analogs bearing exocyclic methylenes in different positions is described. Bis-exo-cyclopamine 6 was identified as a potent inhibitor of the Gli1-dependent luciferase expression in Shh-LIGHTII cells. An extension of this study to F-ring-modified structures shows the necessity of a rigidly positioned nitrogen atom for bioactivity as