1-Aza-2-azoniaallene salts: reactions with azomethines and other N-nucleophiles
Abstract
Azomethines undergo nucleophilic addition to 1-aza-2-azoniaallene salts 7 to furnish N-(azoalkyl)iminium salts (e.g. 10, 12, 13). With cyclic hydrazones such as pyrazole or indazole, heterocumulenes 7 afford bicyclic 1,2,4,5-tetrazinium salts (e.g. 14, 16), or simple N-adducts such as 15, 17. On the other hand, with open-chain hydrazones azinium salts 19 are formed. Benzotriazole and the aziridine 21 react with 1-aza-2-azoniaallene salts 7 to afford (azoalkyl)ammonium salts 20, 22. The heterocumulenes 7 undergo cycloaddition across the CN double bond of the azirine 23 to furnish azirenotriazolium salts 25, while with the 1-aza-2-azoniaallene salt 3a the triazolium salt 28 was formed. The constitutions of compounds 22, 25a and 28 were confirmed by X-ray structural analyses.