4-Amino-8-(3-{[4-({3-[4-azido-5-(hydroxymethyl)oxolan-2-yl]-5-methyl-2,6-dioxo(1,3-dihydropyrimidinyl)}methyl)phenyl]methyl}-5-methyl-2,4-dioxo(1,3-dihydropyrimidinyl))-1,7-dioxa-9-(1,1,2,2-tetramethyl-1-silapropoxy)-6-[(1,1,2,2-tetramethyl-1-silapropoxy)methyl]-2-thiaspiro[4.4]non-3-ene-2,2-dione AIDS-122974 AIDS122974