Velpatasvir Impurity 18

Chemical Name: methyl ((S)-1-((2S,5S)-2-(9-(2-((2S,4S)-1-((R)-2-amino-2-phenylacetyl)-4-(methoxymethyl)pyrrolidin-2-yl)-1H-imidazol-5-yl)-1,11-dihydroisochromeno[4',3':6,7]naphtho[1,2-d]imidazol-2-yl)-5-methylpyrrolidin-1-yl)-3-methyl-1-oxobutan-2-yl)carbamate