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A novel and concise synthesis towards DP2 receptor antagonist Fevipiprant (NVS-QAW039) was developed. The initial research route was suffering from lengthy access to the functionalized 7-aza-indole core followed by a low selective N(1)-alkylation with the benzyl side chain. These limitations were overcome by introducing the side chain early via reductive amination between the functionalized aldehyde and 2-amino-3-bromopyridine. Sonogashira coupling with prop-2-yn-1-ol introduces the 3 missing carbon atoms to build the 7-aza-indole core and sets the stage for the innovative Johnson-Claisen key step. Reaction of the advanced propargylic alcohol derivative with trimethyl orthoacetate leads to a reactive allene intermediate that spontaneously and selectively cyclizes to the 7-aza-indole QAW039-methly ester. QAW039 is isolated after ester saponification. Selectivity, yield, and ecological footprint of the new synthesis were significantly improved, and scalability was demonstrated.

The serine protease Factor XI (FXI) is a prominent drug target as it holds promise to deliver efficacious anti-coagulation without an enhanced risk of major bleeds. Several efforts have been described targeting the active form of the enzyme, FXIa. Herein we disclose our efforts to identify potent, selective, and orally bioavailable inhibitors of FXIa. Compound 1, identified from a diverse library of internal serine protease inhibitors, was originally designed as a complement Factor D inhibitor and exhibited sub-micromolar FXIa activity and an encouraging ADME profile while being devoid of peptidomimetic architecture. Optimization of interactions in the S1, S1β, and S1` pockets of FXIa through a combination of structure-based drug design and traditional medicinal chemistry led to the discovery of compound 23 with sub-nanomolar potency on FXIa, enhanced selectivity over other coagulation proteases, and a pre-clinical PK profile consistent with bid dosing in patients.