Imidazo quinoxalines table

From fried beef, another new compound, 2-amino-3,8-dimethy1-imidazo[4,5-/]quinoxaline (MelQx), was isolated, and its structure was confirmed by chemical synthesis (15). The structures of all the compounds isolated from pyrolysates of amino acids and a protein, and from cooked fish and meat, are shown in Table II. 

Table 3. Cyanine Dyes based on Imidazo[4,5-6]quinoxalines.677...

TABLE 3. CYANINE DYES BASED ON IMIDAZO[4,5-6]QUINOXALINES ... 

Table 4.2 Three-component reaction of 3-benzoylquinoxalin-2(l//)-one with aromatic aldehydes and NH4OAC for the synthesis of imidazo[l,5-n]quinoxaline system...

Analysis of the efficiency of different methods of synthesis of imidazo[l,5-a] and imidazo[l,2-fl]quinoxalines demonstrates that there are currently 26 approaches corresponding to the retrosynthetic analysis of the stmcture of a heterocyclic system without including the benzene ring. Initial compounds are quinoxaline (see Figs. 4.3 and 4.6) or imidazole derivatives (see Figs. 4.4 and 4.7). For synthesis of imidazo[l,5-a]quinoxaline, seven approaches based on quinoxalines and four approaches based on imidazoles have been developed (Table 4.4) for synthesis of imidazo[l,2-a]quinoxalines, six approaches based on quinoxalines and five approaches based on imidazoles have been developed (Table 4.5). 

These Tables demonstrate which methods of synthesis of imidazo[l,5-a] quinoxalines are most widely used, which of them require further development, and which methods remain unused. The formation of imidazof 1,5-a]quinoxalines 107 and 108 from compounds 76 and 105, as well as the formation of imidazo[l,2-a]... 

Table 4.4 Comparison of different approaches to the synthesis of imidazo-[l,5-a]quinoxalines (see Figs. 4.3 and 4.4)...

Elchaninov and Elchaninov 2014) reactions. The formation of 2-(lH-imidazo[4,5-Z7]pyridin-2-yl)-3-arylquinoxahnes 96a-d from pyrido[2,3-fe]pyrazin-2(lfl)-ones 95a-d and 1,2-DAB 5a proceeds in AcOH under reflux for 35-47 h. It should be noted, that carrying out the reaction with refluxed AcOH for 3 h leads to the formation of 2-amino-3-azaanylide quinoxaline 3-phenyl-2-carboxylic acids 97. This has been illustrated by the reaction of 2-(lH-imidazo[4,5-fc]pyridin-2-yl)-3-phenylquinoxahne 95a and 1,2-DAB 5a (Table 6.4) (Mamedov et al. 2010a). 

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