Discovery of dehydro-oxopiperazine acetamides as novel bradykinin B1 receptor antagonists with enhanced in vitro potency

In a series of bradykinin B1 antagonists, we discovered that replacement of oxopiperazine acetamides with dehydro-oxopiperazine acetamides provided compounds with enhanced activity against the B1 receptor. The synthesis and SAR leading to potent analogs with reduced molecular weight will be discussed.