Conformationally restricted piperidinyl benzamides as 5-HT3 receptor antagonists.

Abstract The synthesis and 5-HT3 receptor antagonist activity of indolizidin-7-yl and 8-oxaquinolizidin-2-yl benzamides related to the quinolizidine, BRL 20627 (2), are described. High potency is restricted to axial isomers and both the indolizidines and oxa-quinolizidines are much more potent than (2), an effect which appears to be unrelated to basicity.