Diazo-4,5-dicyano-2H-imidazole and Its Reaction Products

This substance is best represented as the diazonium zwitterion 26 since its chemistry is analogous to diazonium ion chemistry rather than to diazoalkane chemistry. Because 26 is a diazonium compound without a counterion, it allows one to study pure diazonium ion chemistry. The diazonium nature of 26 is confirmed by its N- and C-NMR spectra compared to those of p-nitrophenyldiazonium tetrafluoroborate (27) and diazocyclopentadiene (28) (78JA4974). Chemical shifts of the carbon attached to the central nitrogen are in 26,5112.2 from Mc4Si in 27,6 121.8 and in 28,6 72.2. The central nitrogen shift is 6 146.0 from HNO3 for 26,152.2 for 27, and 106.2 for 28. The terminal nitrogen is d 59.4 for 26, 57.1 for Tl, and — 8.8 for 28. 

We first discuss addition reactions of 26, then reactions in which nitrogen is lost. 

The only example of C—C insertion for 26 was noted with hexaflu-orobenzene. The eight/five fused ring system 41 was formed in high yield. Its structure was confirmed by X-ray analysis (80UP1). 

Alcohols. In a reaction reminiscent of diazonium ion chemistry, 26 is reduced by ethanol to 13 (R = H). The ethanol is oxidized to acetaldehyde (72UP1). Like water, decomposition of 26 in f-butanol gives nitrogen in quantitative yield, but the other product is intractable. 

Pyrazines from Diaminomalonitrile (DAMN) and/or Diiminosuccinonitrile (DISN) 

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