4,12a-Methano-2H,12aH-naphtho[2,3-b]-1,5-dioxocin-2-one,3,4,6,6a,7,12-hexahydro-6a,7,8,12-tetrahydroxy-6-methyl-,(4R,6S,6aR,7S,12R,12aS)-rel-(-)-