N-[9-[(2R,3R,3aR,7aS,9R,10aS,14aR)-5-(2-Cyanoethoxy)-2-(1,6-dihydro-6-oxo-9H-purin-9-yl)-3-fluorodecahydro-12,12-dioxido-2H-difuro[3,2-d:3′,2′-j][1,7,9,2,3,8]trioxathiaazaphosphacyclododecin-9-yl]-9H-purin-6-yl]benzamide

4H-Imidazo[4,5-d]pyridazin-4-one, 1-[5-O-[bis(4-methoxyphenyl)phenylmethyl]-2-deoxy-β-D-erythro-pentofuranosyl]-1,5-dihydro-