2- Diazo-4,5-dicyano-2//-imidazole

Thermolysis of 2-diazo-4,5-dicyano-2//-imidazole 656 in benzonitrile gives nitrilium ylide 657, which reacts with a second benzonitrile molecule to afford [4+2]-cycloadduct 658 (79JOC1717). Intermediate formation of nitrile ylide 659 was also supported in a reaction of N-fluoropyridinium... 

The tetracyano derivative of 2.49, 5-diazo-l,2,3,4-tetracyanocyclopentadiene (2.52), and its heterocyclic analogue, 2-diazo-4,5-dicyano-imidazole (2.53) can be obtained by diazotization of the corresponding amines, namely the (anionic) 1-amino-... 

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