1,3,2-Dioxaphosphorino[4',5':5,6]pyrano[3,2-g]pteridin-10(4H)-one,8-amino-4a,5a,6,9,11,11a,12,12a-octahydro-2,12,12-trihydroxy-, 2-oxide,(4aR,5aR,11aR,12aS)-