Diethyl {2-[(4-chloro­phen­oxy)meth­yl]-9-(methyl­sulfanyl)-7H-pyrazolo[4,3-d][1,2,4]-triazolo[1,5-d]pyrimidin-7-yl}(phen­yl)methyl­phospho­nate

In the title compound, C25H26ClN6O4PS, the fused pyrazolotriazolopyrimidine ring system is almost planar. It makes dihedral angles of 78.1 (1) and 17.1 (1)°, respectively, with the attached phenyl ring and 4-chloro­phenoxy­methyl fragment. The P atom has a distorted tetra­hedral configuration. Intra- and inter­molecular C—H⋯O and C—H⋯N hydrogen bonds, together with strong π–π stacking inter­actions (inter­planar distances 3.312–3.567 A), stabilize the structure.