Velpatasvir Intermediate (RRS)

Velpatasvir Intermediate (RRS) is a stereoisomeric precursor in the synthesis of the NS5A inhibitor Velpatasvir, characterized by a pyrazine core fused to a tetrahydropyridine ring with RRS absolute configuration at chiral centers. The molecule features a 4-aminobutyl side chain appended to the pyrazine nitrogen and a hydroxyl-substituted phenyl group at the tetrahydropyridine moiety. Structural divergence from the parent drug arises from the absence of a terminal methylsulfonyl group, replaced by a free sulfonamide functionality. This intermediate serves as a critical HPLC reference standard for quantifying stereoisomeric impurities during Velpatasvir API purification.