2-amino-9-((1R,3R,4S)-4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopentyl)-3H-purin-6(9H)-one;2-Amino-1,9-dihydro-9-[(1R,3R,4S)-4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopentyl]-6H-purin-6-one; Entecavir Isomer Impurity 3; (1’R,3’R,4’S)-Entecavir Isomer; Entecavir 1-epimer impurity;1’-epi-Entecavir
