New reactions and processes for the efficient synthesis of a HCV NS5b prodrug

Herein we describe the route scouting and process development efforts toward a green and sustainable synthesis of the HCV NS5b cyclic prodrug nucleoside (CPN) 1. Through the discovery and development of a crystallization-induced dynamic resolution and a novel chemo- and stereo-selective phosphorylation reaction, we eliminated costly chromatographies and protecting group manipulations utilized in the initial approaches to this compound and implemented a highly streamlined and sustainable approach to the target molecule. We demonstrate how these improvements impact the PMI of the API on the kilogram scale and compare our work to the PMI of APIs of similar complexity.