It is thought that selective 5-HT4 receptor agonists—such as 4-amino-5-chloro-2-methoxy-N- [1-(6-oxo-6-phenylhexyl) piperidin-4-ylmethyl] benzamide (2)—have the ability to enhance both upper and lower gastrointestinal motility without any significant adverse effects. Modification of 2 was performed. Variation of the piperidin-4-ylmethyl moiety of 2 led to a decrease in the binding affinity for the 5-HT4 receptor. Following conversion of the ...