.Beta.-D-Erythro-Pentofuranuronic acid, 3-azido- 1,2, 3-trideoxy-1-(3,4-dihydro-5-methyl-2,4-dioxo-1(2H)-pyrimidinyl)- AIDS-142037 AIDS142037 NSC658787 Thymidine, 3'-azido-3'-deoxy-5'-oxo-