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

In the title compound, C20H19N5O2, all atoms of the 1,2,3-triazolo[4,5-d]pyrimidine ring system are essentially coplanar [maximum deviation = 0.015 (2) Å], indicating the existence of a conjugate system in which each carbon and nitrogen atom is sp 2 hybridized and ten π electrons (three from carbon atoms and seven from nitrogen atoms) constitute an aromatic heterocycle. The ring system forms dihedral angles of 68.37 (10) and 71.57 (9)° with the phenyl rings. The crystal packing is stabilized by van der Waals interactions and intermolecular C—H⋯π interactions.

In the title compound, C 20 H 19 N 5 O 2 , all atoms of the 1,2,3triazolo[4,5-d]pyrimidine ring system are essentially coplanar [maximum deviation = 0.015 (2) Å ], indicating the existence of a conjugate system in which each carbon and nitrogen atom is sp 2 hybridized and ten electrons (three from carbon atoms and seven from nitrogen atoms) constitute an aromatic heterocycle. The ring system forms dihedral angles of 68.37 (10) and 71.57 (9) with the phenyl rings. The crystal packing is stabilized by van der Waals interactions and intermolecular C-HÁ Á Á interactions.
In recent years, we have been engaged in the preparation of derivatives of 8-azaguanine via aza-Wittig reaction of betaethoxycarbonyl 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 beta-ethoxycarbonyl iminophosphorane with alphalic isocyanate, and structurally characterized in this context.
The crystal packing is stabilized mainly by van der Waals interactions, no intermolecular hydrogen bonds or π-π stacking interactions being observed. One of the methyl H atoms is involved in a contact to the centroid (Cg) of the C15/C20 phenyl ring (C13-H13A···Cg = 2.75 Å), which may be considered as a C-H···π interaction.

Experimental
To a solution of carbodiimide in CH 2 Cl 2 /CH 3 CN (1:4 v/v, 15 ml) prepared according to the literature method (Wang et al., 2006), was added phenol (3 mmol) and excess K 2 CO 3 , 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 (yield 75%; m.p. Crystals suitable for single-crystal X-ray diffraction analysis were obtained by slow evaporation of a hexane/dichlorometh-

K). Elemental analysis
supplementary materials sup-2 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.