Quinoxalinecarbonyl halides

Ethyl 3-bromomethyl-6,7-difluoro-2-quinoxalinecarboxylate 1,4-dioxide (84) gave 6-fluoro-2-methyl-7-methylamino-2,3-dihydro-17/-pyrrolo[3,4-h]quinoxalm-l-one 4,9-dioxide (85) (MeCN, MeNH2i, 15°C, 90 min 87% note additional replacement of one fluoro substituent) analogs likewise. °  

Ethyl 3-formyl-2-quinoxalinecarboxylate 1,4-dioxide (86) gave 2-phenylpyrida-zino[4,5-h]quinoxaline-l(277)-one (87) (excess PhNHNH2, EtOH, reflux, 2h  

These useful intermediates are frequently used cmde without characterization as such. 

Preparation. Virtually aU quinoxalinecarbonyl chlorides have been made by treatment of the corresponding quinoxalinecarboxylic acids with thionyl chloride (see Section 7.1.2). 

Reactions. Quinoxalinecarbonyl chlorides are occasionally used to make the corresponding quinoxalinecarboxylic esters (see Section 7.2.1) but more often to make quinoxalinecarboxamides or the like. Typical examples of such reactions follow. 

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Several routes to such derivatives have been covered already by primary synthesis (Chapter 1), from quinoxalinecarboxylic acids (Section 7.1.2), from quinoxalinecarboxylic esters (Section 7.2.2), and from quinoxalinecarbonyl halides (Section 7.3). Other preparative routes are illustrated in the following classified examples. 

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