2,4(1H,3H)-Pyrimidinedione, 1-[(6R,8R,9R)-4-amino-9-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-6-[[[(1,1-dimethylethyl)dimethylsilyl]oxy]methyl]-2,2-dioxido-1,7-dioxa-2-thiaspiro[4.4]non-3-en-8-yl]-5-methyl-3-propyl- AIDS-215969 AIDS215969 TSAO Deriv.