Monocyclic and bicyclic himbacine derivatives useful as thrombin receptor antagonists

What is this patent about?

’377 is related to the field of medicinal chemistry and pharmacology, specifically focusing on the development of synthetic compounds that modulate cellular receptors involved in blood clotting and inflammation. The invention addresses the need for effective therapies for cardiovascular diseases and inflammatory conditions by targeting the thrombin receptor, also known as protease activated receptor-1 (PAR-1), and the cannabinoid CB2 receptor. These receptors play critical roles in platelet aggregation, vascular smooth muscle proliferation, and immune system signaling.

The underlying idea behind ’377 is the structural modification of himbacine, a naturally occurring piperidine alkaloid, to create nor-seco himbacine derivatives that exhibit potent antagonistic activity. The inventive insight lies in simplifying and rearranging the tricyclic core of himbacine while introducing specific heterocyclic and aromatic substituents. By optimizing the side chains and the connectivity between the polycyclic scaffold and a substituted pyridyl group, the inventors achieved high affinity for PAR-1, which is essential for preventing pathological thrombosis without necessarily increasing bleeding risks associated with traditional anticoagulants.

The claims of ’377 focus on a specific class of compounds defined by a core structure that includes a substituted pyridyl group linked via an alkenylene bridge to a monocyclic or bicyclic system. Independent claim 1 defines the broad structural formula, emphasizing the requirement for a pyridyl group (Het) substituted by various moieties (W) and a specific bridging unit (B). The claims also encompass pharmaceutically acceptable salts and specify the stereochemical arrangements that provide the desired biological activity against thrombin and cannabinoid receptors.

In practice, the invention works by utilizing these small molecules to competitively bind to the thrombin receptor on the surface of human platelets and vascular cells. This binding prevents thrombin from triggering the signaling cascade that leads to platelet aggregation and arterial blockage. The synthesis involves converting carboxylic acid precursors into aldehydes, which are then coupled with phosphonates to build the unsaturated bridge and the terminal heteroaromatic ring. This modular synthetic approach allows for the fine-tuning of the compound's lipophilicity and binding kinetics.

The ’377 invention differs from prior approaches by moving away from peptide-based thrombin receptor antagonists, which often suffer from poor oral bioavailability and rapid metabolic degradation. Unlike earlier tricyclic himbacine analogs, these nor-seco derivatives offer a distinct topological profile that enhances their potency as PAR-1 antagonists. By incorporating a substituted pyridyl group specifically at the terminus of the side chain, the compounds achieve a more favorable interaction within the receptor's binding pocket, providing a more robust therapeutic window for treating acute coronary syndrome and thrombotic stroke.