Synthesis, crystal structure, Hirshfeld surface analysis, DFT and NBO study of ethyl 1-(4-fluorophenyl)-4-[(4-fluorophenyl)amino]-2,6-diphenyl-1,2,5,6-tetrahydropyridine-3-carboxylate

Abstract

The title compound, C32H28F2N2O2, a highly functionalized tetrahydropyridine, was synthesized by a one-pot multi-component reaction of 4-fluoroaniline, ethyl acetoacetate and benzaldehyde at room temperature using sodium lauryl sulfate as a catalyst. The compound crystallizes with two molecules in the asymmetric unit. The tetrahydropyridine ring adopts a distorted boat conformation in both molecules 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 intramolecular N—H...O hydrogen bond, thereby generating an S(6) ring motif. In the crystal, molecules are linked by C—H...F hydrogen bonds forming a three-dimensional network and C—H...π interactions. 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.