Scalable Syntheses of Pseudouridine and N1-Methylpseudouridine.

Pseudouridine (Ψ) is a naturally occurring C-nucleoside featuring a C-C glycosidic bond. When incorporated into mRNA, it confers reduced immunogenicity and enhanced translational efficiency, driving advances in mRNA vaccine research. Its derivative, N1-methylpseudouridine (m1Ψ), played a pivotal role in the successful deployment of COVID-19 mRNA vaccines. Herein, we report two synthetic routes for Ψ and m1Ψ. The first enables gram-scale laboratory syntheses of both C-nucleosides. The second, optimized to address specific process challenges, facilitates kilogram-scale industrial production. These developments are expected to accelerate the application of these modified nucleosides in next-generation mRNA vaccine development.