Ethyl aminotetrazoles

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]. 

Treatment of ethyl l-oxo-l//-pyrimido[l,2-a]quinoline-2-carboxylates with ammonia in methanol and hydrazine hydrate in ethanol at ambient temperature afforded 2-carboxamides and 2-carbohydrazides, respectively (74MIP1 79MIP2). Reaction of l-oxo-l//-pyrimido[l,2,-a]quinoline-2-carboxylic acids (169) with A-. /V-carbonyldiimidazole in dimethyl-formamide, then with 5-aminotetrazole gave 7V-(5-tetrazolyl)-1 -oxo-1H-pyrimido[l,2-a]quinoline-2-carboxamides (170) (77GEP2630469 77USP 4017625). 

Amino-2-ethyl-2//-tetrazole, 1264 5-Aminotetrazole, 0460 5-Azidotetrazole, 0387 Barium 5,5 -azotetrazolide, 0574 l,6-Bis(5-tetrazolyl)hexaaza-l,5-diene, 0823... 

Ethy 1 aminotetrazoles. See under Amino-ethyl tetrazoles A206-R 5-Ethylamino-a tetrazole A207-L Ethylaminotriazoles. See under Amino-ethyltriazoles A207-R ... 

Various aryl aldehydes 196 have been cyclized with 5-aminotetrazole 197 and pyruvic acid 195 catalyzed by iodine in refluxing ethyl acetate (Scheme 13.47). 

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