5-Aminotetrazole

Attempted diazotization in dilute acid sometimes yields primary nitroso compounds. Reactions of 3- and 5-amino-1,2,4-thiadiazoles with sodium nitrite and acid give primary nitrosamines (e.g. 432->433) (65AHC(5)n9) which can be related to the secondary nitrosamines (434) prepared in the normal way. 1-Substituted 5-aminotetrazoles with nitrous acid give stable primary nitrosamines (435). Primary nitrosamines have been isolated in the imidazole series. 

The thermal conversion of 1-substituted 5-aminotetrazole (423) into a 5-substituted aminotetrazole (424) can be rationalized by a similar 1,5-dipolar cyclization. 

In the same way, l-substituted-5-aminotetrazoles react with benzyl chloride to give 1-substituted 4-benzyl-5-iminotetrazolines. ... 

The 3-formyl group of 8-substituted 3-formyl-2-hydroxy-4//-pyrido[l,2-n]pyrimidin-4-one was reacted with (cyanomethyl)- and (terr-butoxycarbo-nylmethylene)triphenylphosphorane in THF, and with 5-aminotetrazole in boiling MeOH for 9h to yield ( )-3-propenenitrile, terr-butyl ( )-3-propenoate and 3-[(2//-tetrazol-5-yl)imino]methyl derivatives, respectively (OlMIPl). 

The high reactivity of heterocyclic diazonium ions in azo coupling reactions is the reason why in some cases the primary diazotization products cannot be isolated. For example, diazotization of 2-methyl-5-aminotetrazole (2.14) directly yields the triazene 2.15, i. e., the N-coupling product, since the intermediate diazonium ion is reactive enough to give the N-coupling product with the parent amine even under strongly acidic conditions (Scheme 2-8 Butler and Scott, 1967). 

See 5-Aminotetrazole Nitrous acid See other DIAZONIUM SALTS, TETRAZOLES... 

Diazotised 5-aminotetrazole is unstable under the conditions recommended for its use as a biochemical reagent. While the pH of the diazotised material (the cation of which contains 87% nitrogen) at 0°C was being reduced to 5 by addition of potassium hydroxide, a violent explosion occurred [1], This may have been caused by a local excess of alkali causing the formation of the internal salt, 5-diazoniotetrazolide, which will explode in concentrated solution at 0°C [2], The diazonium chloride is also very unstable in concentrated solution at 0°C. Small-scale diazotisation (2 g of amine) and susequent coupling at pH 3 with ethyl cyanoacetate to prepare ethyl 2-cyano-(l//-tetrazol-5-ylhydrazono)acetate proceeded uneventfully, but on double the scale a violent explosion occurred [3], The importance of adequate dilution of the reaction media to prevent explosions during diazotisation is stressed [4]. 

Aminotetrazole reacts with 4,5-dichloro-l,2,3-dithiazolium chloride 166 to afford the bis(imino-l,2,3-dithiazole) 167 (20%) which in warm DMSO or DMF converts into the 1,2,3-clithiazolimine 168 (25%) (Scheme 16) <2002J(P1)1535>. 

Other approaches to tetrazoles were also recently published. Primary and secondary amines 195 were reacted with isothiocyanates to afford thioureas 196, which underwent mercury(II)-promoted attack of azide anion, to provide 5-aminotetrazoles 197 . A modified Ugi reaction of substituted methylisocyanoacetates 198, ketones, primary amines, and trimethylsilyldiazomethane afforded the one-pot solution phase preparation of fused tetrazole-ketopiperazines 200 via intermediate 199 <00TL8729>. Microwave-assisted preparation of aryl cyanides, prepared from aryl bromides 201, with sodium azide afforded aryl tetrazoles 202 . 

The synthesis of the polycyclic 5-5-6-5 derivative 81 was realized by nucleophilic substitution of the 5,6-dichloro[ 1,2,5]oxadiazolo[5,4-7]pyrazine 79 with 5-aminotetrazole 80 (Scheme 17). This conversion took place at room temperature and the product 81 was isolated in moderate 36% yield. Many other heterocyclizations with N,N, N,0-, /V,.Y-bidentate nucleophiles gave the corresponding reaction in up to 93% yield <1997CHE1352>. 

In Scheme 20, another ring closure starting from 5-aminotetrazole is shown, which should be discussed in more detail. Nenajdenko and co-workers carried out studies on ring closure reactions taking place between 1,1,1-trifluoro-4-sulfonyl-but-3-ene-2,2-diols 107 and a series of aminoazoles <2002S901>. They found that the reaction can take place in two different ways and, thus, the isomers 108 and 109 can be formed. Reaction of 107 with 5-aminotetrazole 106 was found to proceed regioselectively, and yielded the 5-trifluoromethyl compound 108 as the main product in good yield (72%). The other isomer 109 was found only in traces. 

Table 9 Synthesis of tetrazolo[1,5-a]pyrimidines starting from 5-aminotetrazole...

Acetyl-4-(4/-sulfophenyl)-3-tetrazene, 2982 Aluminium azide, 0082 Aluminium tetraazidoborate, 0059 Amino guanidine, 0507 1-Amino-3-nitroguanidine, 0495 5-Aminotetrazole, 0461 5-Amino-l,2,3,4-thiatriazole, 0413... 

Opening, as has also been observed in the Dimroth rearrangement of 5-aminotetrazoles (see Section IV,B,l,a). 

Scheme 29). The reaction of 5-aminotetrazole with diphenylacetylene may similarly involve the intermediacy of hydrazoic acid. ... 

The high nitrogen content and the endothermic nature of the tetrazole ring lends itself to the synthesis of energetic materials. Compounds such as -H tetrazole and 5-aminotetrazole can be used as nucleophiles to incorporate the tetrazole ring into other molecules. 5-Aminotetrazole is synthesized from the reaction of dicyandiamide with sodium azide in hydrochloric acid. 

The reaction of 5-aminotetrazole with 3,5-diamino-2,4,6-trinitrofluorobenzene generates the energetic tetrazole (151). ... 

Nitrotetrazole is readily prepared from the diazotization of 5-aminotetrazole in the presence of excess sodium nitrite and is best isolated as the copper salt complex with ethylenediamine. The salts of 5-nitrotetrazole have attracted interest for their initiating properties. The mercury salt is a detonating primary explosive. The amine salts of 5-nitrotetrazole are reported to form useful eutectics with ammonium nitrate. ... 

Treatment of the bis(pyrazoyl)tetrazine (197) with an excess of hydrazine hydrate generates 3,6-bis(hydrazino)-l,2,4,5-tetrazine (208), a compound which might find use as an energetic additive in high performance propellants. Several salts of (208) have been reported, including the dinitrate and diperchlorate. 3,6-Dichloro-l,2,4,5-tetrazine (209), the product from treating (208) with chlorine in acetonitrile, reacts with the sodium salt of 5-aminotetrazole (210) to yield (211) (C4H4N14 - 79 % N). ... 

The reaction of aminoguanidine bicarbonate (84) with sodium nitrite in the presence of excess acetic acid produces 1,3-ditetrazolyltriazine (89), another nitrogen-rich heterocycle (C2H3N11 = 85 % N) which readily forms explosive metal salts. The reaction of aminoguanidine bicarbonate (84) with sodium nitrite in the presence of mineral acid yields guanyl azide (90), of which, the perchlorate and picrate salts are primary explosives. Guanyl azide (90) reacts with sodium hydroxide to form sodium azide, whereas reaction with weak base or acid forms 5-aminotetrazole. ... 

Aminotetrazole (91) reacts with potassium permanganate in excess aqueous sodium hydroxide to yield the disodium salt of 5-azotetrazole (92). 5-Azotetrazole is unstable and attempts to isolate it by acidification yields 5-hydrazinotetrazole (93). Diazotization of 5-aminotetrazole (91) in the presence of excess sodium nitrite yields 5-nitrotetrazole (94), a powerful explosive whose mercury and silver salts are primary explosives. ... 

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