The design and synthesis of a series of highly functionalized pyrano-[2, 3b]-pyridines is described. These compounds were assayed for their ability to block the IKur channel encoded by the gene hKV1. 5 in patch-clamped L-929 cells. Six of the compounds in this series showed sub-micromolar activity, the most potent being 4-(4-ethyl- benzenesulfonylamino)-3-hydroxy-2, 2-dimethyl-3, 4-dihydro-2H-pyrano [2, 3b]-pyridine-6 ...