Improved Synthesis of a Key Intermediate of Onapristone

We report a novel, single-step, and scalable synthesis of ONA-3, a key advanced intermediate of onapristone. The process strategically employs an inexpensive starting material ONA-2 that also serves as an advanced intermediate in mifepristone production, ensuring a steady material supply on a metric ton scale. Compared to existing methods, this streamlined approach dramatically reduces the estimated cost of goods (COGS) to 32% and the manufacturing cycle time to 20%. Ultimately, this concise and highly cost-effective manufacturing process provides a strengthening solution to the supply chain challenges of onapristone.