Sofosbuvir IMpurity B (S)-isopropyl 2-(((S)-(((2R,3R,4R,5R)-4-chloro-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-3-hydroxy-4-methyltetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)amino)propanoate Sofosbuvir impurity K Sofosbuvir Chloro Analogue L-Alanine, N-[[P(S),2'R]-2'-chloro-2'-deoxy-2'-methyl-P-phenyl-5'-uridylyl]-, 1-methylethyl ester Sofosbuvir Chloro Analog sofosbuvir impurity Y008005-K (2S)-isopropyl 2-(((((2R,3R,4R,5R)-4-chloro-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-3-hydroxy-4-methyltetrahydrofuran-2-yl)methoxy)(phenoxy)phosphoryl)amino)propanoate