Methyl 6-quinoxalinyl ketone

Reactions of 2-chloro- and 2,3-dichloroquinoxalines with carbanions give 2-quinoxalinyl ketones and 3-chloro-2-quinoxalinyl ketones, respectively e.g., 2-quinoxalinylacetophenone (151) from acetophenone anion.161 However, 2,3-dimethoxy- and 2,3-diethoxy-quinoxaline with methyl ethyl ketone and sodamide in anhydrous benzene give 2-amino derivatives rather than ketones.162... 

An alternative to qdt, (.S )-2-(3-mercaptoquinoxalinyl)thiourinium, is stable and soluble in aqueous ethanol solutions unlike qdt (27). At pH 10 in ammonia-ammonium chloride buffer, this reagent hydrolyzes to qdt. (5)-2-(3-Mercapto-quinoxalinyl)thiourinium has been used for the simultaneous detection of nickel and cobalt and the determination of palladium (27, 28). A related reagent, 6-nitro-(S)-2-(3-mercaptoquinoxalinyl)thiourinium has also been used in metal analysis (7). This reagent is hydrolyzed in ammonia buffer to generate 6-nitro-2,3-quinoxalinedithiol (nqdt). Following adjustment to pH 2.0, the mixture is extracted with methyl isobutyl ketone and spectrophotometrically analyzed. 6-Nitro-(5)-2-(3-mercaptoquinoxalinyl)thiourinium has been used for the simultaneous spectrophotometric determination of nickel and cobalt by the quantification of [Ni(nqdt)2]2 (710 nm, e = 20,700 L mol 1cm 1) and [Co(nqdt)2]2 (530 nm, e = 40,000 L moE cm-1), respectively. 

The IR spectrum of 2-acetyl-3-methylquinoxaline shows carbonyl stretching absorption at 1695 cm in Nujol and therefore in the region to be expected of an aryl methyl ketone. A range of standard derivatives have been prepared from quinoxalinyl ketones (see Table 1) but cycliza-tion occurs on treatment of various 2-benzoylquinoxalines (10) with... 

Alkyl and arylmagnesium halides react with 2-methylquinoxaline by addition of one mole of reactant to the 3,4-bond. After hydrolysis the 2-alkyl- or 2-aryl-l,2-dihydro-3-methylquinoxalines (52) are obtained. When ethylmagnesium bromide is used a dimeric by-product (53) is also isolatedReaction of 2,3-dimethylquinoxaline with benzonitrile and lithium amide gives l-amino-l-phenyl-2-(3-methyl-2-quinoxalinyl)-ethylene (54). The mono- and dilithium salts of 2,3-dimethylquinoxaline have been generated from the quinoxaline by reaction with one or two equivalents of lithium diisopropylamide (LiNPr, respectively. These salts have been reacted with a variety of electrophilic reagents such as alkyl halides, aryl ketones, esters, and nitriles. " ... 

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