2.3- Dimethylpyrido pyrazine oxidation

Partially hydrogenated pyrazine moieties in pyrido[2,3-6]pyrazines are aromatized by permanganate11,67 or iodine.7 Thus, ethyl 8-amino-3,4-dihydro-2-methylpyrido[2,3-6]pyrazine-6-carba-mate (1) with potassium permanganate in acetone yields 84% of the fully aromatic compound 2,11 another example being the oxidation of l,2,3,4-tetrahydro-2,3-dimethylpyrido[2,3-A]pyrazine (3)-67 nh2 nh2... 

Whereas 2,3-dimethylpyrido[2,3-A]pyrazine is unaffected by hydrogen peroxide in glacial acetic acid at 70 °C, the 7-bromo compound gives an Ar-oxide under these conditions.32... 

Dimethyl-1,2,3,4-tctrahydropyrido[3,4-6]pyrazine, obtained by the action of methyl-magnesium iodide on the parent compound (cf. Section 7.2.3.2.2.2.2.), is easily aromatized by air oxidation during workup, yielding 2,3-dimethylpyrido[3,4-i>]pyrazine.67... 

Oxidation of 2,3-dimethylpyrido[2,3-f)]pyrazine with potassium permanganate gave the 2,3-dicarboxylic acid, isolated as the lead salt. Similarly alkaline potassium permanganate at about 60° oxidizes various... 

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