2,4(1H,3H)-Pyrimidinedione, 1-[(2R,5S)-5-[[(4-butyl-5-chloro-2-oxido-4H-1,3,2-benzodioxaphosphin-2-yl)oxy]methyl]-2,5-dihydro-2-furanyl]-5-methyl- AIDS-188478 AIDS188478