(S)-2-((2-amino-6-oxo-3H-purin-9(6H)-yl)methoxy)ethyl 2-(ethylamino)-3-methylbutanoate;2-[(2-Amino-6-oxo-1,6-dihydro-9H-purin-9-yl)methoxy]ethyl N-Ethyl-L-valinate
(S)-2-((2-amino-6-oxo-3H-purin-9(6H)-yl)methoxy)ethyl 2-(ethylamino)-3-methylbutanoate;2-[(2-Amino-6-oxo-1,6-dihydro-9H-purin-9-yl)methoxy]ethyl N-Ethyl-L-valinate