The synthesis of a number of indole GnRH antagonists is described. Oxidation of the pyridine ring nitrogen, combined with alkylation at the two position, led to a compound with an excellent in vitro activity profile as well as oral bioavailability in both rats and dogs. ... The synthesis and biological evaluation of a series of indole GnRH receptor antagonists are described. Several potent binders of the human GnRH receptor were discovered, including compound 44, ...