The chemistry of nitrilium salts. Part 4. Some reactions of 5-amino-4(C-cyanoformimidoyl)imidazoles obtained from nitrilium trifluoromethanesulphonate salts and diaminomaleonitrile

Abstract

Diaminomaleonitrile (DAMN) has been found to react readily with the nitrilium trifluoromethanesulphonate (triflate) salts [R¹CNMe]⁺ŌTf (R¹= Ph or Me) to give the amidinium salts [MeH¹C(CN)C(CN)NH₂]⁺ŌTf, which, after base treatment under different conditions, afford 5 amino-4-carbamoylimidazoles, 5-amino-4-cyanoimidazoles, or 5-amino-4-(C-cyanoformimidoyl)imidazoles. The amidinium salts react with aldehydes and ketones at room temperature to give 6-carbamoyl-1,2-dihydropurinium salts; this reaction is accelerated in the presence of a small amount of pyridine. Similarly, 5-amino-4-(C-cyanoformimidoyl)-1,2-dimethylimidazole reacts with aldehydes, ketones, 1,2- and 1,3-diketones, and keto esters to give 6-carbamoyl-1,2-dihydropurines, which', in some cases are readily oxidised in air to the corresponding 6-carbamoylpurines.