Herein we report for the first time a one-pot method for the synthesis of pentacyclic pyran fused pyrazolo benzo[h]quinolines in acetic acid medium from the threecomponent reaction of 2-hydroxy-1,4-naphthoquinone, α, βunsaturated aldehydes and 5-aminopyrazoles under the reflux conditions. In this reaction, four new bonds (2 CÀ C, 1 CÀ N and 1 CÀ O) and two new rings (pyridine and pyran) were formed in one-pot. The novel products contain four bioactive moieties such as pyran, pyridine, pyrazole and α-naphthol. The salient features of this method are: one-pot process, short reaction time, easier purification, no need of column chromatography and good yields of the products. All the products were characterized by IR, NMR and HRMS. Most of our synthesized compounds were found highly fluorescent. Therefore, we further studied their photophysical properties by UV-Visible and Fluorescence spectroscopy. We have calculated their quantum yields which were found in the range 0.243-0.424 in CHCl 3 solution (c = 10 À 5 M). Compound 4 e showed the highest quantum yield of 0.424.

No abstract

Herein we have reported a one‐pot green methodology for the synthesis of quinoline tethered α‐amino ketones. The reaction of arylglyoxal, 2‐aminoquinoline, and 4‐hydroxy‐1‐methylquinolin‐2(1H)‐one/barbituric acid in ethanol under reflux conditions provided the quinoline tethered α‐amino ketones. The environmentally benign process, one‐pot synthesis, readily available starting materials, short reaction time, easy purification process, good yields of the products, and the presence of several bioactive moieties such as quinolines and α‐amino carbonyl in the product are the main advantages of this methodology. All the products were characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (1H NMR), 13C NMR, and high‐resolution mass spectrometry (HRMS). Single‐crystal X‐ray diffraction (XRD) of one compound was also reported.

Herein, a hitherto unreported approach for the synthesis of pyrazole/isoxazole-fused naphthyridine derivatives by a three-component domino reaction of arylglyoxal monohydrate, 5-amino pyrazole/isoxazole, and indoles in acetic acid medium has been reported. In this method, four bonds (2 C–C and 2 C–N) form in one-pot with the concomitant formation of two new pyridine rings via indole ring opening and double cyclization reactions. This methodology is also applicable in gram-scale synthesis. The reaction mechanism was studied by isolating and characterizing the reaction intermediates. Along with complete characterization of all the products, the structure of the product 4o was unambiguously confirmed by single crystal X-ray diffraction.