Di Boc Velpatasvir impurity 1 is a di-tert-butyloxycarbonyl-protected derivative of Velpatasvir, characterized by two Boc groups appended to its terminal amine functionalities. The core structure retains the sulfonamide-linked triazole and cyclopropylmethyl substituents of the parent NS5A inhibitor but features additional steric bulk from the Boc moieties. This impurity arises during synthetic deprotection steps, where incomplete removal of protecting groups occurs. It serves as a critical HPLC reference standard for monitoring process purity in Velpatasvir API manufacturing.
