Neutral macrocyclic factor VIIa inhibitors.

Factor VIIa (FVIIa) inhibitors have shown strong antithrombotic efficacy in preclinical thrombosis models with limited bleeding liabilities. Discovery of potent, orally active FVIIa inhibitors has been largely unsuccessful due to the requirement of a basic P1 group to interact with Asp189 in the S1 binding pocket, limiting their membrane permeability. We have combined recently reported neutral P1 binding substituents with a highly optimized macrocyclic chemotype to produce FVIIa inhibitors with low nanomolar potency and enhanced permeability.

Discovery of Phenylglycine Lactams as Potent Neutral Factor VIIa Inhibitors.

Inhibitors of Factor VIIa (FVIIa), a serine protease in the clotting cascade, have shown strong antithrombotic efficacy in preclinical thrombosis models with minimal bleeding liabilities. Discovery of potent, orally active FVIIa inhibitors has been largely unsuccessful because known chemotypes have required a highly basic group in the S1 binding pocket for high affinity. A recently reported fragment screening effort resulted in the discovery of a neutral heterocycle, 7-chloro-3,4-dihydroisoquinolin-1(2H)-one, that binds in the S1 pocket of FVIIa and can be incorporated into a phenylglycine FVIIa inhibitor. Optimization of this P1 binding group led to the first series of neutral, permeable FVIIa inhibitors with low nanomolar potency.

Structure-Based Design of Macrocyclic Coagulation Factor VIIa Inhibitors.

On the basis of a crystal structure of a phenylpyrrolidine lead and subsequent molecular modeling results, we designed and synthesized a novel series of macrocyclic FVIIa inhibitors. The optimal 16-membered macrocycle was 60-fold more potent than an acyclic analog. Further potency optimization by incorporation of P1' alkyl sulfone and P2 methyl groups provided a macrocycle with TF/FVIIa Ki = 1.6 nM, excellent selectivity against a panel of seven serine proteases, and FVII-deficient prothrombin time EC2x = 1.2 µM. Discovery of this potent, selective macrocyclic scaffold opens new possibilities for the development of orally bioavailable FVIIa inhibitors.

Nonbenzamidine acylsulfonamide tissue factor-factor VIIa inhibitors.

Aminoisoquinoline and isoquinoline groups have successfully replaced the more basic P1 benzamidine group of an acylsulfonamide factor VIIa inhibitor. Inhibitory activity was optimized by the identification of additional hydrophobic and hydrophilic P' binding interactions. The molecular details of these interactions were elucidated by X-ray crystallography and molecular modeling. We also show that decreasing the basicity of the P1 group results in improved oral bioavailability in this chemotype.

An Unusual Trifluoromethyl Elimination Reaction from the 4,4-Bis(trifluoromethyl)-5-hydroxyimidazoline Ring System.

A facile detrifluoromethylation was observed when 4,4-bis(trifluoromethyl)-5-hydroxyimidazoline 5 was treated with a variety of bases to afford the biologically interesting 4-(trifluoromethyl)imidazole analogs (9 and 10). A unique mechanism was proposed for this transformation, supported by isolating and trapping the hypothesized intermediates. Heating of 5 with Et(4)NCN in DMSO provided 19, which was clearly derived from the proposed intermediate 17. Finally, imidazole 9 was converted into the N-[2-phenyl-4-(trifluoromethyl)-1H-imidazol-5-yl]-N-methylbenzamide analogs, which were potential acyl CoA:cholesterol acyltransferase (ACAT) inhibitors.