Pyrido pyrazines table

Little is known about the chemistry of pyridylfuroxans, but reaction of the [l,2,5]oxadiazolo[3,4-Z>]pyridine oxides (126) and (127) with activated methylene synthons provides pyrido[2,3-6]pyrazine-1,4-dioxides (130) in moderate yields (Beirut reaction) (Table 4, Scheme 21) <80M407, 82AF10). The actual reactive species is presumed to be the bis(nitroso)pyridine isomer (128). Direct oxidation... 

Table 11.5 Synthesis of pyrido[3,4-b]pyrazine and imidazopyridine scaffolds [47, 56]... 

Pyrido[2,3]pyrazines can be prepared by thermal cyclization of enaminones derived from 2-aminopyrazines (Table VIII, entry 5). 

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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