N-{2-[(4S)-4-tert-Butyl-4,5-dihydro-1,3-oxazol-2-yl]phenyl}-5,6-diphenyl-1,2,4-triazin-3-amine

The title compound, C28H27N5O, was synthesized using palladium cross-coupling amination of 3-bromo-5,6-diphenyl-1,2,4-triazine with 2-[(4S)-4-tert-butyl-4,5-dihydro-1,3-oxazol-2-yl]aniline. The oxazoline ring is almost planar, with a maximum atomic deviation of 0.023 (5) Å. The phenyl rings make dihedral angles of 29.0 (1) and 54.6 (1)° with the triazine ring while the benzene ring makes a dihedral angle of 0.6 (1)° with the oxazoline ring. The conformation of the molecule is influenced by strong intramolecular N—H⋯N and weak C—H⋯N hydrogen bonds. In the crystal, screw-axis related molecules are linked into supramolecular chains by intermolecular C—H⋯O hydrogen bonds. π–π stacking is observed between the oxazoline and triazine rings of adjacent molecules, with a centroid–centroid distance of 3.749 (2) Å.


Comment
Compounds containing a chiral oxazoline ring have proven to be one of the most successful ligand classes for asymmetric catalysis. A diverse range of di-, tri-and tetradentate oxazoline ligands incorporating various heteroatoms and specific structural features have been synthesized and used in a wide range of metal catalyzed asymmetric processes (Desimoni et al., 2006;Hargaden et al., 2009). Introduction of 1,2,4-triazine ring into ligand structure can significantly increase ligand binding properties, since 1,2,4-triazine is known as a good metal chelator (Lindsey et al., 2004). Due to our interest in developing new oxazoline-based ligands the titled compound was synthesized and its application in asymmetric catalysis is currently under investigation.
Crystals suitable for X-ray diffraction analysis were grown by slow evaporation of a methanol solution.

Refinement
In the absence of significant anomalous scattering, Friedel pairs were merged and the absolute configuration was assigned from the absolute configuration of started 2-[(4S)-4-tert-butyl-4,5-dihydro-1,3-oxazol-2-yl]aniline. All H atom were located by difference Fourier synthesis. N-bound H atom was refined freely. The remaining H atoms were treated as riding on their C atoms, with C-H distances of 0.93 (aromatic) and 0.96 Å (CH 3 ). All H atoms were assigned U iso (H) values of 1.5U eq (N,C).
Figures Fig. 1. The molecular structure of (I), with atom labels and 50% probability displacement ellipsoids for non-H atoms.  Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
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 > 2sigma(F 2 ) is used only for calculating R-factors(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.