117723-56-5 5-Et-D4U 5-Ethyl-2',3'-didehydro-2',3'-dideoxyuridine 5-Ethyl-2'-deoxyuridin-2'-ene AIDS-000078 AIDS000078 D4EtU Uridine, 2',3'-didehydro-2',3'-dideoxy-5-ethyl-