Synthetic Development and Scale-Up of a Complex Pyrazole Fragment of Lenacapavir

We describe herein the process development and scale-up of a complex cyclopropyl pyrazole fragment of lenacapavir, a drug recently approved for long-acting treatment of HIV (Sunlenca). A ten-step asymmetric synthesis was developed utilizing simple starting materials capable of supporting the commercial supply chain of lenacapavir. Key aspects of this development effort were the oxidation strategy to elaborate the core and optimization of the fluorination reaction to afford the final product.