7-Substituted 2-phenyl-benzofurans as ERβ selective ligands

A series of 2-(4-hydroxy-phenyl)-benzofuran-5-ols with relatively lipophilic groups in the 7-position of the benzofuran was prepared and the affinity and selectivity for ERβ was measured. Many of the analogues were found to be potent and selective ERβ ligands. Additional modifications at the benzofuran 4-position as well as at the 3′-position of the 2-phenyl group were found to further increase selectivity. Such modifications led to compounds with <10 nM potency and >100-fold selectivity for ERβ.