Design and synthesis of novel proline based factor XIa selective inhibitors as leads for potential new anticoagulants.

A series of 4, 4-disubstituted proline analogs were designed, synthesized, and tested for selective inhibition of blood coagulation factor XIa in search of new non-vitamin K antagonists based oral anticoagulants for potential prevention and treatment of thrombotic diseases. Starting from a potent thrombin (FIIa) inhibitor chemotype with FIIa IC50 = 1 nM and FXIa IC50 = 160 nM, medicinal chemistry iterations guided by molecular modeling and structure-based drug design led to steady improvement of FXIa potency while dialing down thrombin activity and improving selectivity. Through this exercise, a thousand-fold enhancement of selectivity over thrombin was achieved with some analogs carrying factor XIa inhibition potencies in the 10 nM range. In this communication, we discuss the design principles and structure activity relationship (SAR) of these novel FXIa selective inhibitors.

Imidazopyridyl compounds as aldosterone synthase inhibitors.

The inhibition of aldosterone synthase (CYP11B2) may be an effective treatment of hypertension and heart failure, among other ailments. Previously reported benzimidazole CYP11B2 inhibitors led the way for bioisosteric imidazopyridines that are both potent and selective over CYP11B1.

N-Substituted tertiary and O-substituted quaternary carbon stereogenic centers by site-, diastereo- and enantioselective vinylogous Mannich reactions.

A readily accessible small-molecule phosphine, derived from commercially available starting materials such as an enantiomerically pure amino acid, serves as the precursor to a Ag-based chiral complex that can be prepared and used in situ to promote a variety of enantioselective vinylogous Mannich (EVM) reactions that involve siloxypyrroles as reaction partners. Transformations with unsubstituted nucleophilic components proceed efficiently and with exceptional site- (γ vs α-addition), diastereo- and enantioselectivity [up to 98% yield, generally >98:2 γ/α and diastereomeric ratio (dr) and up to 99:1 enantiomeric ratio (er)]. The first examples of efficient, diastereo- and enantioselective vinylogous Mannich additions with 5-methyl-substituted siloxyfuran, resulting in the formation of O-substituted quaternary carbon stereogenic centers are presented as well. Appreciable efficiency and diastereo- and enantioselectivity (up to >98:2 dr and >99:1 er) is accompanied by formation of α-addition products that can be oxidatively removed.

Si-free enolate Claisen rearrangements of enamido substrates.

α-Alkyl ß-amino esters are available in high diastereoselectivity through a silicon-free Claisen enolate [3,3]-sigmatropic rearrangement of enamide esters. Optimisation studies have probed the crucial role of the initial enolisation and the nature of the enamide N-centre. The demonstration of chirality transfer and the formation of ß-proline systems, is also presented.

High-resolution crystal structures of factor XIa coagulation factor in complex with nonbasic high-affinity synthetic inhibitors.

Factor XI (FXI) is a key enzyme in the coagulation pathway and an attractive target for the development of anticoagulant drugs. A small number of high-resolution crystal structures of FXIa in complex with small synthetic inhibitors have been published to date. All of these ligands have a basic P1 group and bind exclusively in the nonprime side of the active site of FXIa. Here, two structures of FXIa in complex with nonbasic inhibitors that occupy both the prime and nonprime sides of the active site are presented. These new structures could be valuable in the design and optimization of new FXIa synthethic inhibitors.

Optimization of TEAD P-Site Binding Fragment Hit into In Vivo Active Lead MSC-4106.

The dysregulated Hippo pathway and, consequently, hyperactivity of the transcriptional YAP/TAZ-TEAD complexes is associated with diseases such as cancer. Prevention of YAP/TAZ-TEAD triggered gene transcription is an attractive strategy for therapeutic intervention. The deeply buried and conserved lipidation pocket (P-site) of the TEAD transcription factors is druggable. The discovery and optimization of a P-site binding fragment (1) are described. Utilizing structure-based design, enhancement in target potency was engineered into the hit, capitalizing on the established X-ray structure of TEAD1. The efforts culminated in the optimized in vivo tool MSC-4106, which exhibited desirable potency, mouse pharmacokinetic properties, and in vivo efficacy. In close correlation to compound exposure, the time- and dose-dependent downregulation of a proximal biomarker could be shown.

Practical and highly enantioselective synthesis of beta-alkynyl-beta-amino esters through Ag-catalyzed asymmetric mannich reactions of silylketene acetals and alkynyl imines.

[reaction: see text] A readily available iso-leucine-based phosphine ligand is used to promote Ag-catalyzed Mannich reactions between silylketene acetals and various alkynyl imines. Reactions can be effected in the presence of 5 mol % catalyst, without the need for rigorous exclusion of air, and with commercially available solvents (without purification) to afford the desired beta-alkynyl-beta-amino esters in 84-94% ee and 61-91% isolated yield.

Discovery of Benzimidazole CYP11B2 Inhibitors with in Vivo Activity in Rhesus Monkeys.

We report the discovery of a benzimidazole series of CYP11B2 inhibitors. Hit-to-lead and lead optimization studies identified compounds such as 32, which displays potent CYP11B2 inhibition, high selectivity versus related CYP targets, and good pharmacokinetic properties in rat and rhesus. In a rhesus pharmacodynamic model, 32 produces dose-dependent aldosterone lowering efficacy, with no apparent effect on cortisol levels.

A practical protocol for the highly E-selective formation of aryl-substituted silylketene acetals.

The E/Z-selectivity in the formation of silylketene acetals derived from phenylacetate esters, mediated by LiHMDS, has been studied by in situ NMR techniques. The formation is seen to be highly E-selective with use of the newly developed protocol. Isolated aryl-substituted silylketene acetals are now attainable with high levels of E-geometrical purity in excellent yield.