Synthesis and structures of three new pyridine-containing oxazoline ligands of complexes for asymmetric catalysis

Three new chiral pyridine-containing oxazoline derivatives with fluorine and perfluoro­methyl groups, namely, 2-({2-[(4S)-4-phenyl-4,5-di­hydro-1,3-oxazol-2-yl]phen­yl}amino)-5-(tri­fluoro­methyl)­pyridine, C21H16F3N3O, 2-({5-fluoro-2-[(4S)-4-isopropyl-4,5-di­hydro-1,3-oxazol-2-yl]phen­yl}amino)-5-(tri­fluoro­methyl)­pyridine, C18H17F4N3O, and 2-({2-[(3aR,8aS)-8,8a-di­hydro-3aH-in­deno­[1,2-d]oxazol-2-yl]phen­yl}amino)-5-(tri­fluoro­methyl)­pyridine, C22H16F3N3O, as chiral ligands in metal-catalysed asymmetric reactions, were synthesized and characterized by spectral and X-ray diffraction methods. The conformation of the mol­ecules is influenced by strong N—H⋯N hydrogen bonding and weak C—H⋯X (X = O and N) inter­actions. There are no inter­molecular hydrogen bonds in the crystal structures of the analysed com­pounds. Hirshfeld surface analysis showed that the H⋯H contacts constitute a high percentage of the inter­molecular inter­actions. The conformational analysis was performed by theoretical calculations using the density functional theory (DFT) method. The mechanism of com­plex formation in terms of the electron-withdrawing effect of the substituents on the oxazoline ring and the ligand conformation is discussed.