Cyclization of n-alkylazinium cations with bisnucleophiles. 5. Cyclic adducts and recyclization products in the reactions of benzodiazinium cations with imido esters

Article abstract of DOI:10.1007/BF00506467

The reaction of imido esters that contain an active methylene group with four isomeric benzodiazinium cations, viz., the 1-methylquinoxalinium, 2-methylcinnolinium, 3-methylquinazolinium, and 2-methylphthalazinium cations, was investigated. The 1-methylquinoxalinium cation reacts with imido esters via a scheme involving anionic [3^- +2]-cycloaddition to form tetrahydropyrrolo[2,3-b]quinoxalines. The 2-methylcinnolinium cation forms an adduct with an annelated pyrrole ring. Under the influence of imido esters, the 3-methylquinazolinium cation undergoes recyclization to a 2,3-disubstituted quinoline. The 2-methylphthalazinium cation is inert in this reaction.