Synthesis, structure, and photoisomerization of derivatives of 2-(2-quinolyl)-1,3-tropolones prepared by the condensation of 2-methylquinolines with 3,4,5,6-tetrachloro-1,2-benzoquinone

• Published in: Tetrahedron 2010-11, Vol.66 (45), p.8763-8771
• Main Authors: Sayapin, Yury A., Duong, Bang Nghia, Komissarov, Vitaly N., Dorogan, Igor V., Makarova, Nadezhda I., Bondareva, Inna O., Tkachev, Valery V., Shilov, Gennady V., Aldoshin, Sergey M., Minkin, Vladimir I.
• Format: Article
• Language: English
• Subjects: 1,3-Tropolones; Derivatives; Electrocyclic rearrangement; Equivalence; Heptanes; Intermolecular hydrogen bond; Mathematical analysis; Molecular structure; Photolysis; Tetrahedrons; X-rays
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2010.08.077

A series of novel derivatives of the 1,3-tropolone (β-tropolone) system—2-(2-quinolyl)-5,6,7-trichloro-1,3-tropolones and 2-(2-quinolyl)-4,5,6,7-tetrachloro-1,3-tropolones have been prepared by the acid-catalyzed reaction of 2-methylquinolines with 3,4,5,6-tetrachloro-1,2-benzoquinone. The molecular structures of two compounds, 2-(4-chloro-6,8-dimethyl-5-nitro-2-quinolyl)-5,6,7-trichloro-1,3-tropolone 8 and 2-(4-chloro-7,8-dimethyl-5-nitro-2-quinolyl)-4,5,6,7-tetrachloro-1,3-tropolone 9, have been determined using X-ray crystallography. According to the performed DFT B3LYP/6-311++G ∗∗ calculations the tautomeric (OH) and (NH) forms of β-tropolones 8 and 9 are nearly energy equivalent, the latter being more stabilized in polar media. Photolysis of 2-(2-quinolyl)-1,3-tropolones in heptane solution leads to the disrotatory electrocyclic rearrangement resulting in the formation of a mixture of E- and Z-isomers of 3-[2(1 H)-quinolinylyden]-bicyclo[3.2.0]hept-6-en-2,4-dione derivatives. [Display omitted]