Synthesis and Evaluation of 17α-Arylestradiols as Ligands for Estrogen Receptor α and β

To identify novel estrogen receptor ligands a series of substituted 17 alpha-arylestradiols were synthesized using the catalytic [2 + 2 + 2]cyclotrimerization of 17 alpha-ethynylestradiol with various 1,7-diynes in the presence of Wilkinson's catalysts [Rh(PPH3)(3)Cl]. The compounds were subjected to competitive binding assays, cell-based luciferase reporter assays, and proliferation assays. These experiments confirmed their estrogenic character and revealed some interesting properties like mixed partial/full agonism for ER alpha/ ER beta and different selectivity as a result of differing potencies for either ER.