Synthesis of 4-(8-benzo[1,2,5]oxadiazol-5-yl-[1,7]naphthyridine-6-yl)-benzoic acid: a potent and selective phosphodiesterase type 4D inhibitor

The synthesis of a 6,8-disubstituted 1,7-naphthyridine 1 and its characterization as a potent and selective phosphodiesterase type 4D inhibitor (IC50=1.5nM) are described. The compound inhibited TNFα-release from human peripheral blood mononuclear cells and was orally active in a model of adjuvant-induced arthritis in rats.