Aroylguanidine-based factor Xa inhibitors: The discovery of BMS-344577

We report the design and synthesis of a novel class of N,N′-disubstituted aroylguanidine-based lactam derivatives as potent and orally active FXa inhibitors. The structure–activity relationships (SAR) investigation led to the discovery of the nicotinoyl guanidine 22 as a potent FXa inhibitor (FXa IC₅₀ = 4 nM, EC_2×PT = 7 μM). However, the potent CYP3A4 inhibition activity (IC₅₀ = 0.3 μM) of 22 precluded its further development. Detailed analysis of the X-ray crystal structure of compound 22 bound to FXa indicated that the substituent at the 6-position of the nicotinoyl group of 22 would be solvent-exposed, suggesting that efforts to attenuate the unwanted CYP activity could focus at this position without affecting FXa potency significantly. Further SAR studies on the 6-substituted nicotinoyl guanidines resulted in the discovery of 6-(dimethylcarbamoyl) nicotinoyl guanidine 36 (BMS-344577, IC₅₀ = 9 nM, EC_2×PT = 2.5 μM), which was found to be a selective, orally efficacious FXa inhibitor with an excellent in vitro liability profile, favorable pharmacokinetics and pharmacodynamics in animal models.