Synthesis and spectral investigation of some new hetaryl-substituted hydroquinolinone derivatives

Magnetic nanocomposite based on chitosan-gelatin hydrogel embedded with copper oxide nanoparticles: A novel and promising catalyst for the synthesis of polyhydroquinoline derivatives

Nanocatalysts are vital in several domains, such as chemical processes, energy generation, energy preservation, and environmental pollution mitigation. An experimental study was conducted at room temperature to evaluate the catalytic activity of the new gelatin-chitosan hydrogel/CuO/Fe3O4 nanocomposite in the asymmetric Hantzsch reaction. All components of the nanocomposite exhibit a synergistic effect as a Lewis acid, promote the reaction. Dimedone, ammonium acetate, ethyl acetoacetate, and other substituted aldehydes were used to synthesize diverse polyhydroquinoline derivatives. The nanocomposite exhibited exceptional efficacy (over 90 %) and durability (retaining 80 % of its original capacity after 5 cycles) as a catalyst in the one-pot asymmetric synthesis of polyhydroquinoline derivatives. Also, turnover numbers (TON) and turnover frequency (TOF) have been checked for catalyst (TON and TOF = 50,261 and 100,524 h-1) and products. The experiment demonstrated several benefits, such as exceptional product efficacy, rapid reaction time, functioning at ambient temperature without specific requirements, and effortless separation by the use of an external magnet after the reaction is finished. The results suggest the development of a magnetic nanocatalyst with exceptional performance. The composition of the Ge-CS hydrogel/CuO/Fe3O4 nanocomposite was thoroughly analyzed using several methods including FT-IR, XRD, FE-SEM, EDX, VSM, BET, and TGA. These analyses yielded useful information into the composition and characteristics of the nanocomposite, hence further enhancing the knowledge of its possible uses.

Synthesis and Structure of Hetaryl Substituted 2,5-dioxo-1,2,3,4,5,6,7,8- Octahydroquinolines

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-octahydro-quinoline-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, 13C-NMR, and mass spectral methods. Furthermore, the structures were verified with the help of 2D (HSQC and HMBC), spin decoupling, and NOE NMR techniques.

5-Oxo-hexahydroquinoline: an attractive scaffold with diverse biological activities

5-Oxo-hexahydroquinoline (5-oxo-HHQ) represents a biologically attractive fused heterocyclic core. Various synthetic analogs of 5-oxo-HHQ have been synthesized and assessed for different biological activities. Some derivatives have exhibited myorelaxant, analgesic, anticancer, antibacterial, antifungal, antitubercular, antimalarial, antioxidant, anti-inflammatory, multidrug resistance reversal, anti-Alzheimer, neuroprotective, antidiabetic, antidyslipidemic and antiosteoporotic activities. This review provides a comprehensive report regarding the preparation and pharmacological characterization of 5-oxo-HHQ derivatives that have been reported so far. This information will be beneficial for medicinal chemists in the field of drug discovery to design and develop new and potent therapeutical agents bearing the 5-oxo-HHQ nucleus.

Crystal structure and metabolic activity of 4-(thien-2-yl)-2-methyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carb-oxy-lic acid eth-oxy-carbonyl-phenyl-methyl-ester

In the title compound, C25H25NO5S, which exhibits metabolism-regulating activity, the 1,4-di-hydro-pyridine ring adopts a flattened boat conformation while the cyclo-hexenone ring is in an envelope conformation. Mol-ecules in the crystal are assembled into C(6) chains along the a-axis direction via N-H⋯O hydrogen bonds. The thienyl fragment is disordered over two sets of sites in a 0.7220 (19):0.2780 (19) ratio.

Study of E/Z isomerization of (arylamino)methylidenefuran-2(3H)-ones by 1 H, 13 C, 15 N spectroscopy and DFT calculations in different solvents

The structure and configuration of the series of previously unknown arylaminomethylidenefuran-2(3H)-ones have been determined in solution by ¹ H, ¹³ C, ¹⁵ N nuclear magnetic resonance spectroscopy including two-dimensional experiments such as ¹ H─¹ H COSY, dqCOSY, ¹ H─¹³ C HSQC, ¹ H─¹³ C HMBC. It was found that synthesized substances exist as an equilibrium mixture of E- and Z-enamines in solution. It was established on the basis of density functional theory calculations that the exchange between the two push-pull enamines is a simple rotation around an exocyclic partial double bond that depends on the effect of the solvents. Copyright © 2017 John Wiley & Sons, Ltd.