Synthesis and evaluation of novel modified γ-lactam prostanoids as EP4 subtype-selective agonists.

To identify chemically and metabolically stable subtype-selective EP4 agonists, design and synthesis of a series of modified γ-lactam prostanoids has been continued. Prostanoids bearing 2-oxo-1,3-oxazolidine, 2-oxo-1,3-thiazolidine and 5-thioxopyrrolidine as a surrogate for the γ-hydroxycyclopentanone without a troublesome 11-hydroxy group were identified as highly subtype-selective EP4 agonists. Among the tested, several representative compounds demonstrated in vivo efficacy after oral dosing in rats. Their pharmacokinetic and structure-activity relationship studies are presented.