A three-step pathway from (2-amino­phenyl)chal­cones to novel styryl­quinoline–chalcone hybrids: synthesis and spectroscopic and structural characterization of three examples

• Published in: Acta crystallographica. Section C, Structural chemistry Structural chemistry, 2023-01, Vol.79 (Pt 1), p.3-11
• Main Authors: Vera, Diana R., Mantilla, Juan P., Palma, Alirio, Díaz Costa, Iván, Cobo, Justo, Glidewell, Christopher
• Format: Article
• Language: English
• Subjects: Research Papers
• ISSN: 2053-2296
• DOI: 10.1107/S2053229622011263

Three new styryl­quinoline–chalcone hybrids are been syntheized using a three-step reaction sequence. In two of them, a combination of hydro­gen bonds and π–π stacking inter­actions generates three-dimensional assemblies, but in the third, only a single weak π–π stacking inter­action is present, linking the mol­ecules into chains. Three new styryl­quinoline–chalcone hybrids have been synthesized using a three-step pathway starting with Friedländer cyclo­condensation between (2-amino­phen­yl)chalcones and acetone to give 2-methyl-4-styryl­quinolines, followed by selective oxidation to the 2-formyl analogues, and finally Claisen–Schmidt condensation between the formyl inter­mediates and 1-acetyl­naph­tha­lene. All inter­mediates and the final products have been fully characterized by IR and 1 H/ 13 C NMR spectroscopy, and by high-resolution mass spectrometry, and the three products have been characterized by single-crystal X-ray diffraction. The mol­ecular conformations of ( E )-3-{4-[( E )-2-phenyl­ethen­yl]quinolin-2-yl}-1-(naph­tha­len-1-yl)prop-2-en-1-one, C 30 H 21 NO, (IVa), and ( E )-3-{4-[( E )-2-(4-fluoro­phen­yl)ethen­yl]quinolin-2-yl}-1-(naph­tha­len-1-yl)prop-2-en-1-one, C 30 H 20 FNO, (IVb), are very similar. In each com­pound, the mol­ecules are linked into a three-dimensional array by hydro­gen bonds, of the C—H⋯O and C—H⋯N types in (IVa), and of the C—H⋯O and C—H⋯π types in (IVb), and by two independent π–π stacking inter­actions. By contrast, the conformation of the chalcone unit in ( E )-3-{4-[( E )-2-(2-chloro­phen­yl)ethen­yl]quinolin-2-yl}-1-(naph­tha­len-1-yl)prop-2-en-1-one, C 30 H 20 ClNO, (IVc), differs from those in (IVa) and (IVb). There are only weak hydro­gen bonds in the structure of (IVc), but a single rather weak π–π stacking inter­action links the mol­ecules into chains. Comparisons are made with some related structures.