Catalytic Asymmetric Synthesis of the Anti-COVID-19 Drug Remdesivir.

The catalytic asymmetric synthesis of the anti-COVID-19 drug remdesivir has been realized via the coupling of the P-racemic phosphoryl chloride with protected nucleoside GS441524. The chiral bicyclic imidazole catalyst is crucial for the dynamic kinetic asymmetric transformation (DyKAT) to proceed smoothly with high reactivity and excellent stereoselectivity [96% conv., 22:1 P(S):P(R)]. Mechanistic studies showed that this DyKAT is a first-order visual kinetic reaction dependent on catalyst concentration. The unique chiral bicyclic imidazole skeleton and carbamate substituent of the catalyst are both required for the racemization process involving the phosphoryl chloride and subsequent stereodiscriminating step. A 10-gram scale reaction was also conducted with comparably excellent results, showing its potential for industrial application.