2,4(1H,3H)-Pyrimidinedione, 1-[3-[(Z)-butylideneoxidoamino]-2,3-dideoxy-5-O-[(1,1-dimethylethyl)dimethylsilyl]-.beta.-L-erythro-pentofuranosyl]-5-methyl- AIDS-161343 AIDS161343 NSC687020