Daclatasvir coupled amine

Daclatasvir coupled amine is a structurally defined impurity arising from the amidation of the parent NS5A inhibitor's sulfonamide moiety. It retains the dibenzofuran-pyridine core but features an additional secondary amine linkage at the C-terminus, forming a stable amide bond with the terminal carboxylic acid. This impurity originates from incomplete coupling during synthetic amidation steps, resulting in a substituted amine with altered H-bonding capacity. The compound exhibits distinct HPLC retention due to its modified hydrophobicity, serving as a critical reference standard for quantifying amidation efficiency in API synthesis.