Crystal structure and synthesis of benzimidazole substituted acrylonitriles and benzimidazo[1, 2-a]quinolines

Abstract

The benzimidazole compounds and benzoannulated cyclic benzimidazole analogues, such as benzimidazo[1,2-a]quinolines, are a part of our wider investigation on biologically active compounds, potential antitumor drugs. Here, we present the synthesis of two compounds,[2-(1H-benzimidazol-2-yl)-3-(4-bromophenyl)-acrylonitrile, 5] and [2-bromo-benzimidazo[1,2-a]quinoline-6-carbonitrile, 7] and their crystal structures revealed by X-ray single crystal diffractometry. We also report the molecular and crystal structures of two additional compounds [2-(1H-benzimidazol-2-yl)-3-(4-cyanophenyl)-acrylonitrile, 4] and [benzimidazo[1,2-a]quinoline-2,6-dicarbonitrile, 6], whose synthesis and spectroscopic characterization have been published earlier by us too (Hranjec and Karminski-Zamola, Molecules 12:1817, 2007). The compounds 4 and 5 crystallize as monohydrates. The dihedral angles calculated between phenyl and benzimidazole ring reflect not significant deviation from molecular planarity in the crystalline state for 4 and 5, while benzoannulated cyclic benzimidazole derivatives 6 and 7 are essentially planar. The crystal structures of 4 and 5 are characterized by O-HÁÁÁN and N-HÁÁÁO hydrogen bonds between water molecule of crystallization and imidazole NH group as well as CN group, while in 6 and 7 only weak C-HÁÁÁN intermolecular hydrogen bonds exist. Although, crystal packings are analogous in 4 and 5, the molecular conformations differ slightly. In 6 there is one C-HÁÁÁN hydrogen bond that do not exist in 7.

“Solvent-Less” Mechanochemical Approach to the Synthesis of Pyrimidine Derivatives

“…An ORTEP plot along with atom numbering scheme is shown in Figure A. The detailed analysis of the bond lengths is summarized in Tables S1 and S2. − In the structure, the benzimidazole moiety adheres to its usual planar nature and is approximately orthogonal to the 2-pyridine moiety with a dihedral angle of 81.59° between the least-squares planes containing the 2-pyridine and benzimidazole moieties. The molecules are arranged in the form of dimers through N–H···N hydrogen bonds (N3–H3A···N1 = 2.089 Å), as shown in Figure B.…”

Novel aminated benzimidazo[1,2-a]quinolines as potential fluorescent probes for DNA detection: Microwave-assisted synthesis, spectroscopic characterization and crystal structure determination

“…These values are comparable for similar benzimidazo[1,2-a]quinoline molecular systems substituted at position 2 with the angle range 0.65(6)o [29]e4.27(4) [7]. The piperidine substituent at C13 in 5 is rotated around C13-N4 single bond (Table 4) (Table 4), as it is found in analogous benzimidazo[1,2-a] quinolines [7,37].…”

“…The C3eH3,,,N2 intermolecular hydrogen bond is found in both structures 4 and 5, while in 4 the proton acceptor cyano N3 atom participates in hydrogen bond formation with phenyl eCH group, and in 5 with less acidic methylene eCH 2 group of piperidine ring. The analogous hydrogen bonding arrangement has been observed in the crystal structures of benzimidazo [1,2-a] quinolines [7,37]. The p,,,p aromatic stacking [38e41] in 4 and 5 are not analogous.…”