This report describes the development of novel benzamides which are orally active, highly potent, specific antagonists of 5-HT3 receptors. Described in this fist report are the structure- activity relationships that led to novel structures with improved potency and selectivity. From this series of compounds,(S)-28 was identified and selected for further evaluation as a 5- HT3 receptor antagonist. Compared with 5-HT3 antagonists such as GR 38032F, BRL ...