Title:Synthesis and Structure of Hetaryl Substituted 2,5-dioxo-1,2,3,4,5,6,7,8-
Octahydroquinolines
Volume: 19
Issue: 5
Author(s): Kadri Gokhan Ozokan*Seniz Kaban*
Affiliation:
- Department of Chemistry, Faculty of Science, Yildiz Technical University, Davutpasa Campus, Istanbul, 34220, Turkey
- Department of Chemistry, Faculty of Science, Yildiz Technical University, Davutpasa Campus, Istanbul, 34220, Turkey
Keywords:
Octahydroquinoline, knoevenagel, enaminone, spin decoupling, NOE, HSQC, HMBC, stereoisomeric configuration.
Abstract:
Aims and Objective: Condensation of 5-hetarylidene-2,2-dimethyl-1,3-dioxane-4,6-
diones with 5,5-dimethyl-3-arylamino-2-cyclohexanones yields 1-aryl-4-hetaryl-7,7-dimethyl-2,5-
dioxo-l,2,3,4,5,5,7,8-octahydro-quinolines. The structures of all the synthesized compounds have
been verified by IR, 1H-NMR, 13C-NMR, and mass spectral methods. The 13C-NMR assignments
were supported by HSQC and HMBC experiments. Moreover, spin decoupling and NOE
experiments have been carried out in order to elucidate stereoisomeric configurations of the
compounds. It has been established that the N-phenyl ring, which projects from the plane of the
octahydroquinolinedione ring, has a shielding effect on the magnetic field of the protons at 7- and
8-positions of the ring in the molecules of the compounds synthesized.
Materials and Methods: The NMR spectra were recorded on a Varian Gemini spectrometer [400
MHz (1H) and 100 MHz (13C)]. EI mass spectra were obtained with a Hewlett Packard GC/MS
6890/5973 machine. MALDI-TOF mass measurements were recorded on a Bruker auto-flex III
smart beam.
Results: Various reaction conditions were applied in order to find an optimum and convenient
procedure for the formation of octahydroquinoline derivates having hetaryl group. The highest
yields (40-50 %) were achieved using acetic acid as solvent, p-toluenesulphonic acid as acidic
catalyst, and excess enaminone (1.5 equiv).
Conclusion: We synthesized eight new 1-aryl-7,7-dimethyl-4-hetaryl-1,2,3,4,5,6,7,8-octahydroquinoline-
2,5-dione compounds containing thienyl core as a result of Michael addition reaction of
Knoevenagel products of Meldrum’s acid with dimedone enaminone compounds. Optimum
circumstances were established using various reaction conditions and catalyzers throughout the
research. The structures of all the synthesized compounds were analyzed by IR, 1H-NMR, 13CNMR,
and mass spectral methods. Furthermore, the structures were verified with the help of 2D
(HSQC and HMBC), spin decoupling, and NOE NMR techniques.
