5-Aminotetrazole synthesis

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>. 

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

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 first synthesis of an azido substituted 1,2,4-thiadiazole has been reported <86CC800>. When l-alkyl-5-aminotetrazoles (284) are heated with an excess of thionyl chloride, 3-azido-l,2,4-thia-diazoles (130) are formed via the proposed intermediate (285) (Scheme 65). 

A more extensively investigated precursor to chemically generated C atoms is diazotetrazole (6), which is easily prepared from readily available 5-aminotetrazole (7). " In this method, 7 is converted into the corresponding diazonium chloride 8, which is coated on the walls of a flask and pyrolysed in the presence of a gaseous substrate (Eq. 6). This technique has the drawback that 8 is extremely explosive and only small quantities can be prepared at a time. " However, the synthesis of 7 with a labeled carbon is quite simple, allowing convenient evaluation of the fate of the reacting carbon. " ... 

Mercuric-5-nitrotetrazole [Structure (2.13)] was prepared according to the methods reported by Gilligan et al. [14] and Redman and Spear [15]. Thus, 5-aminotetrazole was treated with sodium nitrite and copper sulfate to obtain Cu(NT)2HNT-4H20 (where NT nitrotetrazole). The copper salt was subsequently converted to the ethylene diamine complex MNT was then obtained by treating the complex with mercuric nitrate in HN03 medium. The precursors and final product were air dried. The synthesis of these compounds is carried out in a fume hood behind a protective polycarbonate shield in a stainless steel reaction vessel. 

Synthesis of tetrazole compds from acid nitriles) 3)R.M.Herbst et al, JOC,16,13SM9(195l) CA 45, 6629-31(1951) (18 refs) (Prepn of various 1— alkyl—5—aminotetrazoles by the interaction of aikyicyanides with hydrazoic acid in benzene so in in the presence of a coned acid some props of... 

Synthesis from tetrazole precursors was reported [60LA159 79JCS(P1)3085], according to which 5-aminotetrazole (388) was cyclo-condensed with 2-hydroxymethylenecyclohexanone to give tetrazolo [l,5-a]quinazoline (389) instead of the expected tetrazolo[5,l-fc] quinazoline (390). 

The synthesis of the 4,5,6,7-tetrahydrotetrazolo[l,5-a]pyrimidine ring started by reacting 5-aminotetrazole with diethyl bromomalonate to afford diethyl(tetrazol-5-ylamino)malonate (633), whose chloroacetylation led to the formation of 634 rather than 636. Treatment with triethylamine induced ring closure of the chloroacetyl derivative to afford the tetrazolo[l,5-ajpyrimidine 635 rather than the isomer 637 (93ACH683) (Scheme 128). 

However, the key disadvantage of the reaction described in [199] is observed in the first step—synthesis of unsaturated ketoacids 236 with very low yields (20-30%) [200]. The same authors [201] proposed a multicomponent approach to azolopyr-imidinecarboxylic acids. The reactions of pyruvic acid 239 and aromatic aldehydes 240 with 2-aminobenzimidazole, 5-aminotetrazole 156 and 3-amino-1,2,4-triazole 147 in alcohols, DMF and acetic acid were studied (Scheme 3.67). 

The exocyclic amino group of 5-aminotetrazole is reactive in nucleophilic substitution of halogen atoms in halonitrobenzenes. For example, the synthesis of 5-picrylaminotetrazole 406 is based on this process <1999THS(3)467>. Finally, 5-aminotetrazole and l-methyl-5-aminotetrazole 407 undergo a Mannich reaction with formaldehyde and trinitromethane with formation of products 408 (R = H, Me) . 

Another example of utilizing the amino group of 5-aminotetrazole in medicinal chemistry is the synthesis of quinoline derivative 411 as a potential antidiabetic agent (Equation 73) <2000BML1831>. 

A three-component condensation of 5-aminotetrazole with pyruvic acid and aromatic aldehydes was developed as a procedure for the synthesis of 5-aryl-5,8-dihydrotetrazolo[l,5- ]pyrimidine-7-carboxylic acids 414 (Equation 75) <2005S2597>. 

The synthesis of BENZYL ISOCYANIDE from benzaldehyde via reductive amination with 5-aminotetrazole followed by oxidation of the resultant amine with sodium hypobromite provides a general method for the synthesis of isocyanides. The preparation of BIS(2,2,2-TRICHLOROETHYL) AZODICARBOXYLATE makes available an alternative to dimethyl azodicarboxylate that is not only more reactive in Diels-Alder reactions but whose ester groups can be removed under neutral conditions. 

Fig. 9.8 Two synthetic routes for the synthesis of aminotetrazole (AT, a) and the synthetic route for diaminotetrazole (DAT, b).

A solid-phase supported synthesis of substituted /V-terminal 5-aminotetrazole peptides via electrocyclization of peptidic imidoylazides has been reported <07JCO644>. 

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