134250-24-1 (R) 134250-45-6 (S) 3'-Azido-3'-deoxythymidine-5'-(ethyl methoxy-.beta.-alaninyl)phosphoramidate AIDS-002288 AIDS002288 MeOAlaNHPO3(Et)AZT Thymidine, 3'-azido-3'-deoxy-, 5'-[ethyl (3-methoxy-3-oxopropyl)phosphoramidate], -