2.6- Diamino-3-carboxy-5-chloropyrazine

Attempted preparations of the acid chloride from 2,6-diamino-3-carboxy-5-chloropyrazine under a variety of conditions were unsuccessful (1331) and in that respect it resembled anthranilic acid. 

Diamino-3-carboxy-5-chloropyrazine A, 7V-diphenylcarbamic anhydride (19), an active ester, has been prepared by addition of diphenylcarbamoyl chloride to 2,6-diamino-3-carboxy-5-chloropyrazine and triethylamine in dimethylformamide, (and other similar compounds were also prepared) (1330, 1344, 1345). This compound was better prepared from 2,6-diamino-3-carboxy-5-chloropyrazine and... 

Diamino-3-carboxy-5-chloropyrazine in dimethyl sulfoxide (a) with N,N dicyclohexylcarbodiimide gave 2,6-diamino-3-chloro-5-(2, 5 -dioxopyrrolidin-l ylcarbonyOpyrazine ( ) (962), (6) with dicyclohexylcarbodiimide (and 2-hydrazino pyrimidine) gave 2,6-diamino-3-chloro-5-(A -cyclohexyl-V-cyclohexylcarbamoyl) carbamoylpyrazine (1331), and (c) as its triethylamine salt with V-ethyl-5-phenyl... 

A comparison has been made of the reactivity of active esters (12,19,29,30) of 2,6-diamino-3-carboxy-5-chloropyrazine in reactions with various amines to give amides (1345). Compound (19) was the most reactive followed by (12) and both more reactive than the others (1345). Compound (12) with sulfurylamide in acetonitrile with triethylamine gave 2,6-diamino-3-aminosulfonylcarbamoyl-5-chloropyrazine (463). 

Dimethoxycarbonylpyrazine heated with hydrazine hydrate in ethanol gave some 5,8-dihydroxypyrazino[2,3-with hydrazines (and amines) has been described in Section 2C(2)(a) (961,1330, 1331). An analogous active ester was prepared from 2-amino-3-carboxy-5-chloro-6-methoxypyrazine and with hydrazine in tetrahydrofuran gave 2-amino-5-chloro-... 

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