Design and synthesis of 4-substituted benzamides as potent, selective, and orally bioavailable I(Ks) blockers.

Multiple delayed rectifier potassium currents, including I-Ks are responsible for the repolarization and termination of the cardiac action potential, and blockers of these currents may be useful as antiarrhythmic agents. Modification of compound 5 produced 19(S) that is the most potent IF, blocker reported to date with > 5000-fold selectivity over other cardiac ion channels. Further modification produced 24A with 23% oral bioavailability.