Benzofuro[3,2-b]pyridines as mixed ETA/ETB and selective ETB endothelin receptor antagonists

The discovery, synthesis and structure-activity relationships of a series of novel benzofuro[3,2-b]pyridines as non-selective endothelin ETA/ETB as well as selective ETB receptor antagonists are described. The most potent non-selective inhibitor 7s displayed an IC50 of 21 nM and 41 nM for ETA and ETB receptors, respectively, whereas 7ee merely showed affinity for the ETB receptor (IC50 = 3.6 nM).