Crystal structure of 1,3-bis(6-methoxyquinolin-2-yl)benzene, C ₂₆H₂₀N₂O₂

(Equation presentation) (Table presentation) Source of material The title compound, C26H20N2O2, was prepared by the reaction of p-anisidine with terephthaldialdehyde and N-vinyl-2- pyrrolidone at room temperature. A mixture of p-anisidine (3 mmol) and isophthalaldehyde (1.5 mmol) in anhydrous CH3CN (5 mL) under N2, was stirred at room temperature for 1 hour. BiCl3 (20mol%)was added. Over a period of 20min, a solution the N-vinyl-2-pirrolidone (3.1 mmol) in CH3CN (5 mL) was added dropwise. The resultingmixture was stirred for 8-10 h. After completion of the reaction as indicated by TLC, the reaction mixture was diluted with (15mL) and extracted with ethyl acetate (31/210 mL). The organic layer was separated, and dried with Na₂SO4. The organic solvent was removed in vacuo and the resulting product was purified by column chromatography (silica gel, petroleum ether/EtOAc) to afford pure substances, tetrahydroquinoline and 1,3-bis(6-methoxyquinolin-2-yl)benzene. Analysis: Solid crystalline m.p. 224-227 °C. 1H NMR (400 MHz, CDCl3) 3/2 ppm: 8.90 (1H, s, 2-H), 8.24 (2H, d, 4-H; 6-H, J = 9.2 Hz), 8.17 (2H, d, J = 8.8 Hz, 4'-H; 4''-H), 8.13 (2H, d, J = 9.6 Hz, 8'-Hy 8''-H) 8.0 (2H, d, J = 6.4 Hz, 2'-H y 2''-H), 7.7 (H, t, 5-H, J = 7.6 Hz), 7.4 (2H, d, J = 11.6 Hz, 7'-H y 7''-H), 7.1 (2H,m, 5'-H 5''-H). 13C NMR (400 MHz, CDCl3) 3/2: 157.4 (2), 154.6 (2), 144.1 (2), 140 (2), 135.2 (2), 130.9 (2), 128.3 (1), 127.9 (2), 127.6 (2), 126 (1), 122 (2), 119.1 (2), 104.7 (2), 55.2 (2). Experimental details H atoms were located in the difference Fourier map, but refined with fixed individual displacement parameters, using a riding model with C-H distances of 0.95 Å (for CH), 0.98 Å (for CH3), with Uiso(H) values of 1.2Ueq(C) (for CH) and 1.5Ueq(C) (for CH3). Discussion Heterocyclic compounds, especially those with nitrogen, are the most important class of compounds in the pharmaceutical and agrochemical industries [1]. Quinoline systems in particular constitute a privileged substructure and are found in numerous biologically active natural products and pharmacologically relevant therapeutic agents [2]. These organic molecules have attracted attention of both synthetic and medicinal chemists. Quinoline nucleus has been found to possess a wide range of biological activities, such as anti-allergenic [3], antitumoral [4], antimalarial [5] activities, as representative examples. The title compound (Fig.) crystallizes in space group C2/c. The bond lengths and angles are in the expected ranges. The dihedral angles between the mean plane of the quinoline systems [for the non-H atoms, r.m.s. deviations = 0.012 and 0.006 Å] and the benzene ring are 4.53(12) and 2.96(12)°. In the molecular structure, the most noticeable deviation from planarity are expressed by the torsion angles of the methoxy groups with respect to adjacent quinoline system [C8-O2-C26-C25 = 5.3(3) and C7-O1-C16-C15 = 12.5(3)°]. The structure features weak 3/2-3/2 interactions with a centroid-centroid distance of 3.703(2) Å (Cg1: N12/C11/C20/C19/C18/C13; Cg2i: C1-C6; symmetry code: i: 1/2-x, 3/2-y, 1-z ). (Table presentation).