5,9:7,10a-Dimethano-10aH-(1,3)dioxocino(6,5-d)pyrimidine-4,7,10,11,12-pentol, octahydro-2-imino-, (4R,4aR,5R,7S,9S,10S,10aR,11S,12R)- 81520-41-4