3.5- Diamino-2-cyanopyrazine

Another efficient 1,2-diamine for synthesis of cyanopyrazines is 2,3-diamino-3-phenylthioacrylonitrile 135, an adduct of thiophenol to aminomalononitrile tosylate (Scheme 37). The condensation with phenylglyoxal diethyl acetal affords a mixture of two possible isomers 136 and 137, whose regioselectivity is improved by addition of trifluoroacetic acid finally, the isomer 136 is isolated in 86% yield <2001SC725>. 

The dipole moment of 2-chloro-3-cyanopyrazine has been determined as 3.44D in dioxane (749). Polymers have been prepared from 2,3-diamino-5,6-dicyano-... 

Iminoethers were also prepared from 2-amino-3-cyanopyrazine with ethanolic hydrogen chloride (792, 1218) [the product with guanidine and sodium methoxide in methanol formed 2-amino-3-(C-guanidino-C-iminomethyl)pyrazine (878, 1218)] from 2,6-diamino-3-chloro-5-cyanopyrazine with ethanolic hydrogen chloride at 0 (the product heated with ethanol gave 2,6-diamino-3-chloro-5-triethoxymethyl-pyrazine) (1432) from 2-amino-5-chloro-3-cyanopyrazine the product with... 

A -(2 -imidazolin-2 -yl)amidino]pyrazine (59) (877)) and from 2,6-diamino-3-chloro-5-cyanopyrazine [the product heated with dimethylamine in ethanol at 40° gave 2,6-diamino-3-chloro-5-(A(,A -dimethylamidino)pyrazine] (1361). 2-Chloro-... 

Cyanopyrazine with dicyanodiamide [(NH2CN)2] gave the 2-(4, 6 -diamino-triazin-2 -yl)pyrazine (63), with o-phenylenediamine in the presence of poly-phosphoric acid at 250 gave 2-(benzimidazol-2 -yl)pyrazine, and with hydrazine gave 2-(C-hydrazino-C-iminomethyl)pyrazine, which condensed with benzil to 2-(5, 6 -diphenyl-as-triazin-3 -yl)pyrazine (64) (1441). 

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