Semisynthesis of CRV431.

The non-immune-suppressive cyclophilin inhibitor CRV431 is a clinical candidate to cure nonalcoholic steatohepatitis (NASH) and has the potential to treat liver fibrosis and cancer incidence. Herein we report a concise chemical semisynthesis of CRV431 in four steps from the commercially available cyclosporine, featuring in this the flow-chemistry-based methylenation an intermolecular ring-closing metathesis and a Rh-catalyzed diastereoselective hydrogenation.