Pyrazinecarboxamides reactions

To synthesize pyrazinecarboxylic esters and pyrazinecarboxamides, chloropyrazines were subjected to Pd-catalyzed carbonylation reactions in either alcohols or dialkylamines [44, 45]. 2-Chloro-3,6-dimethylpyrazine (23) was smoothly carbonylated in methanol containing a catalytic amount of Pd(dba)2 and Ph3P to give 2-methoxycarbonyl-3,6-dimethylpyrazine (70). Somewhat lower yields were observed in the preparation of pyrazinecarboxylic diesters under the same conditions. 

This section covers the preparation and reactions of nuclear or extranuclear pyrazinecarboxylic esters, pyrazinecarboximidates, and the like. Pyrazinecarboxylic esters exhibit antimycobacterial activities akin to those of pyrazinecarboxamides 651 the structure-activity relationship of such esters has been studied.656... 

Two important reactions in this category have been covered already Hofmann degradation to pyrazinamines (Section 7.3.1) and hydrolysis to pyrazinecarboxylic acids (Section 8.1.1). The remaining reactions of pyrazinecarboxamides and related derivatives are illustrated in the following examples ... 

Reactions of Pyrazinecarbonyl Halides Pyrazinecarboxamides, Pyrazinecarboxamidines, and Related Derivatives... 

Reactions of Pyrazinecarboxamides and the Like Pyrazinecarbohydrazides and Pyrazinecarbonyl Azides Pyrazinecarbonitriles... 

The product of reaction of pyrazinecarboxamide with Cr + is a dark green complex of chromiumCiii) and the pyrazinecarboxamide radical ion, first characterized in 1965 (see ref. 118 and references cited therein). Evidence has now been presented to show that in reactions with various cobalt(ni) complexes, the effective reducing agent is, not the radical-ion complex but free Cr + present in equilibrium with it (Pz = substituted pyrazine) ... 

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