2-(4-Aminophenyl)-1,3-benzoxazole

In the title molecule, C13H10N2O, the dihedral angle between the benzoxazole ring system and the benzene ring is 11.8 (1)°. In the crystal structure, molecules are linked by intermolecular N—H⋯N hydrogen bonds and π⋯π interactions [centroid–centroid distance = 3.6560 (15) Å] to form a two-dimensional network.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH2630).

Comment
The benzoxazole rings sytem is one of the most common heterocycles in medicinal chemistry. Previous reports revealed that substituted benzoxazoles possess diverse chemotherapeutic activities including antibiotic, antimicrobial, antiviral and antitumor activities (Prudhomme et al., 1986;Vinsova et al., 2005). With this mind, the title compound, (I), was prepared in a series of syntheses to produce new benzoxazole derivatives, and we report the crystal stucture herein.

Experimental
All reagents and solvents were used as obtained without further purification. 4-aminobenzoic acid (13.7 g, 0.1 mol) and 2-aminophenol (10.9 g, 0.1 mmol) were mixed together with polyphosphoric acid (50 g) and heated to 493 K under N 2 atmosphere for 4 h. The reaction mixture was cooled to room temperature and poured into 10% K 2 CO 3 solution.

Refinement
All the aromatic H atoms were located at the geometrical positions with C-H=0.93 Å(aromatic), and the U iso values were set 1.2 times of their carrier atoms. H2A and H2B were found in difference Fourier maps and refined with the constraint of N-H=0.86 Å (amine) and U iso (H)=1.2U eq (N). Fig. 1. Molecular structure of (I), showing the atom-numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level.

Special details
Geometry. All e.s. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.