3H-purine-3-butanoic acid, 6-amino-, ethyl ester InChI=1/C11H15N5O2/c1-2-18-8(17)4-3-5-16-7-15-10(12)9-11(16)14-6-13-9/h6-7H,2-5,12H2,1H ethyl 4-(6-amino-3H-purin-3-yl)butanoate