Molecular iodine: a powerful catalyst for the easy and efficient synthesis of quinoxalines

A convenient synthesis of new pyrazolylquinoxalines from 1,5-benzodiazepine-2-thione

“…The dehydration led to 3-(4-methyl-3,4 dihydro-3-thioxo-2H-1,2,4-triazol-5-yl)methylene-2-oxo-1-(3(5)-phenylpyrazol-5(3)-yl)-1,2,3,4-tetrahydroquinoxaline, 12 (Scheme 3). The structure of compound 12 was confirmed on the basis of its 1 H-, 13 C-NMR, IR, and mass spectral data. The infrared spectrum of 12 showed the C=S absorption band at 1270 cm -1 , the mass spectrum (DCI/NH 3 ) exhibited a major peak at m/z = 416 (MH + ), and the 1 H NMR revealed, in addition to the signals due to vinyl and methylene protons at δ 6.08 and 4.37 ppm, respectively, a signal corresponding to the methyl group at 3.52 ppm.…”

“…The reaction of compound 6 with triethyl orthoformate and triethyl orthoacetate in ethanol furnished exclusively 3-(N-ethoxymethylene)hydrazidomethylene-2-oxo-1-(3(5)-phenylpyrazol-5(3)-yl)-1,2,3,4-tetrahydroquinoxaline, 7, and 3-(N-(1-ethoxyethylene) hydrazidomethylene-2-oxo-1-(3(5)-phenylpyrazol-5(3)-yl)-1,2,3,4-tetrahydroquinoxaline, 8, respectively (Scheme 2), the structures of which were attributed on the basis of their spectral data ( 1 H-, 13 C-NMR, IR, and mass spectra). Further refluxing of 7 in N,N-dimethylformamide induced cyclization leading to product 9 3-(5-oxo-3-pyrazolin-4-yl)-2-oxo-1(3(5)-phenylpyrazol-5(3)-yl)-1,2-dihydro-quinoxaline (Scheme 2).…”

“…Melting points were determined on a Büchi Tottoli apparatus and are uncorrected. Spectra were recorded using the following instruments: IR, Perkin-Elmer 577 (KBr disks); NMR, Bruker AC 250 spectrometer, 250 MHz for 1 H-and 62.89 MHz for 13 . To a solution of 2 15 (10 -2 mole) in 100 mL of EtOH, 1.5 equiv.…”

“…8 We have continued our investigations and prepared new quinoxaline derivatives in the hope that they may possess various pharmacological activities. According to some reviews, [9][10][11][12][13][14][15] quinoxaline derivatives have been prepared by several methods. We describe here the synthesis of new quinoxaline derivatives, using 4-phenyl-l,5-benzodiazepine-2-thione, 1, as starting material.…”

Application of Sulfonic Acid Functionalized Nanoporous Silica (SBA-Pr-SO3H) for One-Pot Synthesis of Quinoxaline Derivatives

“…The yields of products were not good. Improved methods have been reported using the different catalysts including I 2 (Bhosale et al 2005, More et al 2005, SA (Darabi et al 2007), Montmorillonite K-10 (Huang et al 2008), polyaniline-sulfate salt (Srinivas et al 2007), H 6 P 2 W 18 O 62 . 24H 2 O , InCl 3 (Hazarika et al 2007), MnCl 2 (Heravi et al 2008), CuSO 4 .5H 2 O , Zn[(L)proline] , CAN (More et al 2006), Ga(OTf) 3 (Cai et al 2008), PEG-400 (Zhang et al 2010), Pd(OAc) 2 , MnO 2 (Raw et al 2003), keggin heteropoly acid (Huang et al 2009), and IBX (Heravi et al 2006) have been explored.…”