Diazotization of aminoguanidine

ATZ was first successfully prepared by Thiele by diazotization of aminoguanidine nitrate. Aminoguanidine salts (nitrate, carbonate, sulfate) are used for synthesis because free aminoguanidine has low stability. The intermediate azidoformamidine is sufficiently stable to be isolated. The cyclization of azidoformamidine by heating with sodium acetate, sodium carbonate, diluted acid, or an aqueous solution of ammonia yields 5-ATZ [28, 29, 32-34]. 

Besides the diazotization of aminoguanidine, 5-AT can also be synthesized by addition of cyanoguanidine / dicyandiamide ... 

The reaction of aminoguanidine with nitrous acid in the presence of an excess of acetic acid gives also l,3-ditetrazyltriazine(IX).It is possible that 5-aminotetrazole first arises, which then undergoes diazotization and the diazo compound thus formed couples with the remaining aminotetrazole ... 

An alternative, more limited, route to (24) and its derivatives involves the 2-amino compound (326) which results from the reaction of aminoguanidine and the [3, l]benzoxazine (327 Scheme 49) (68CB2106). Diazotization of (326) and then hypophosphorus acid produces 2-substituted derivatives of (24) (70JOC3448). 

Diazotization of 4-[(4-aminophenyl)sulfonamido]-2,6-dimethyl pyrimidine 10, followed by coupling of the diazonium salt with ethyl 3-oxobutanoate 11a or l,3-diphenyl-l,3-propanedione lib, afforded hydrazones 12a,b. Reaction of hydrazone 12a with aminoguanidine nitrate in refluxing acetic acid yielded the pyrazol-3-one 13a in 55% yield (00JIC42) (Scheme 4). 

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