The synthesis of disteroidal macrocyclic molecular rotors by an RCM approach

The syntheses of four macrocyclic molecular rotors are described. The starting oxosteroids, 5b-androsterone, and 23-oxosarsasapogenin, were subjected to Grignard ethynylation followed by Sonogashira coupling with 1,4-diiodobenzene. The obtained acyclic dimers were further transformed into the corresponding 3-esters with terminal double bonds. These compounds were converted into the final products via an RCM protocol.