.alpha.-L-Talofuranuronic acid,5-[[2-amino-5-[(aminocarbonyl)amino]-1-oxopentyl]amino]-1,5-dideoxy-1-(3,4-dihydro-2,4-dioxo-1(2H)-pyrimidinyl)-,(S)- 1-[5'-(L-Citrullyamino)-5'-deoxy-.alpha.-L- talofuranosyluronic acid]uracil 93806-81-6 AIDS-008576 AIDS008576 L-citrullyl UPOC analog