5-(4-Chlorophenoxy)-6-isopropyl-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidin-7(6H)-one

In the title compound, C19H16ClN5O2, the triazolopyrimidine ring system is essentially planar, with a maximum displacement of 0.021 (4) Å, and forms dihedral angles of 1.09 (9) and 87.74 (9)° with the phenyl and benzene rings, respectively. Short intramolecular C—H⋯O and C—H⋯N hydrogen-bonding interactions occur within the molecule. In the crystal structure, molecules are linked by intermolecular C—H⋯O hydrogen bonds into chains parallel to the b axis. In addition, π–π stacking interactions involving the triazole and pyrimidine rings of adjacent molecules are observed, with centroid–centroid distances of 3.600 (3) Å.

In the title compound, C 19 H 16 ClN 5 O 2 , the triazolopyrimidine ring system is essentially planar, with a maximum displacement of 0.021 (4) Å , and forms dihedral angles of 1.09 (9) and 87.74 (9) with the phenyl and benzene rings, respectively. Short intramolecular C-HÁ Á ÁO and C-HÁ Á ÁN hydrogenbonding interactions occur within the molecule. In the crystal structure, molecules are linked by intermolecular C-HÁ Á ÁO hydrogen bonds into chains parallel to the b axis. In addition, stacking interactions involving the triazole and pyrimidine rings of adjacent molecules are observed, with centroidcentroid distances of 3.600 (3) Å .
In recent years, we have been engaged in the preparation of the derivatives of 8-azaguanine via aza-Wittig reaction of /b-ethoxycarbonyl iminophosphorane with aromatic isocyanate (Zhao, Xie et al., 2005). As a continuation of our research for new biologically active heterocycles, the title compound was obtained from /b-ethoxycarbonyl iminophosphorane with alphalic isocyanate, and structurally characterized in this context.
There exist two intramolecular C-H···O and C-H···N hydrogen bonding interactions (Table 1) stabilizing the molecular conformation. The crystal packing is stabilized by intermolecular C-H···O hydrogen bonds forming chains parallel to the b axis, and by π-π stacking interactions occurring between adjacent triazole and pyrimidine rings, with centroid-to-centroid distances of 3.600 (3) Å.

Experimental
To the solution of carbodiimide in CH 2 Cl 2 /CH 3 CN (1:4 v/v, 15 ml) prepared according to the literature method , 4-chlorophenol (3 mmol) and excess K 2 CO 3 were added, and the reaction mixture was stirred for 12 h. The solvent was removed under reduced pressure and the residue was recrystallized from EtOH to give the title compound (

Refinement
H atoms were placed at calculated positions and treated as riding atoms, with C-H = 0.93-0.98 Å, and U iso (H) = 1.2U eq (C) or 1.5U eq (C) for methyl H atoms. Fig. 1. View of the molecule of showing the atom-labeling scheme. Displacement ellipsoids are drawn at 50% probability level. H-atoms are represented by circles of arbitrary size.