Synthesis, crystal structure, Hirshfeld surface analysis, DFT and NBO study of ethyl 1-(4-fluoro-phen-yl)-4-[(4-fluoro-phen-yl)amino]-2,6-diphenyl-1,2,5,6-tetra-hydro-pyridine-3-carboxyl-ate

Abstract

The title com-pound, C₃₂H₂₈F₂N₂O₂, a highly functionalized tetra-hydro-pyridine, was synthesized by a one-pot multi-com-ponent reaction of 4-fluoro-aniline, ethyl aceto-acetate and benzaldehyde at room temperature using sodium lauryl sulfate as a catalyst. The com-pound crystallizes with two mol-ecules in the asymmetric unit. The tetra-hydro-pyridine ring adopts a distorted boat conformation in both mol-ecules and the dihedral angles between the planes of the fluoro-substituted rings are 77.1 (6) and 77.3 (6)°. The amino group and carbonyl O atom are involved in an intra-molecular N-H⋯O hydrogen bond, thereby generating an S(6) ring motif. In the crystal, mol-ecules are linked by C-H⋯F hydrogen bonds forming a three-dimensional network and C-H⋯π inter-actions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (47.9%), C⋯H/H⋯C (30.7%) and F⋯H/H⋯F (12.4%) contacts. The optimized structure calculated using density functional theory (DFT) at the B3LYP/6-311+G(2d,p) level is compared with the experimentally determined molecular structure in the solid state. The HOMO-LUMO behaviour was used to determine the energy gap and the Natural Bond Orbital (NBO) analysis was done to study donor-acceptor interconnections.

Keywords: DFT; Functionalized tetra­hydro­pyridine; Hirshfeld surface analysis; NBO; crystal structure; two-dimensional fingerprint plot.