6-Butyl-5-(4-methyl-phen-oxy)-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidin-7(6H)-one.

In the title compound, C(21)H(21)N(5)O(2), the triazolopyrimidine ring system is essentially planar [maximum displacement = 0.021 (4) Å] and forms dihedral angles of 41.17 (9) and 67.99 (8)° with the phenyl and benzene rings, respectively. The n-butyl side chains is disordered over two positions with an ccupancy ratio of 0.77:0.23. An intra-molecular C-H⋯O hydrogen-bonding inter-action stabilizes the mol-ecular conformation. In the crystal, mol-ecules are linked by inter-molecular C-H⋯O and C-H⋯N hydrogen bonds into a three-dimensional network. In addition, π-π stacking inter-actions involving the triazole and pyrimidine rings of adjacent mol-ecules are observed, with centroid-centroid distances of 3.545 (1) Å.