Aza‐2‐dienes‐1,3. Partie 5. Préparation de N ‐aminoimidazoles, 3 H ‐pyrroles, triazolo[1,2,4][1,5‐ a ]pyrazines et imidazo[1,2‐ a ]pyrazines

2‐Aza‐1,3‐dienes. Access to N ‐Aminoimidazoles, 3 H ‐Pyrroles, [1,2,4]Triazolo[1,5‐ a ]pyrazines, or Imidazo[1,2‐ a ]pyrazines Nucleophilic attack of 5‐(dialkylamino)‐2‐aza‐1,3‐diene‐1,1‐dicarbonitriles (or their 1‐methoxycarbonyl analogous) by hydrazines or hydrazdes gives substituted N ‐aminoimidazoles, [1,2,4]triazolo‐[1,5‐ a ]pyrazines, or α‐dihydrazino derivatives. With α‐amino esters (or analogous), imidazo[1,2‐ a ]pyrazines are produced. Addtion of cyanide anions occurs also with formation of substituted 3 H ‐pyrroles. Structures and rationalisation of this nucleophilic attack are discussed.