Enoldiazonium ions

Levisalles and co-workers466 and Wentrup and Dahn467 studied enoldiazonium ions generated under superacidic conditions. More recently Laali and coworkers468 have shown that the stability of enoldiazonium ions can be greatly enhanced by an a-silyl functionality. Equation (4.137) shows the characteristic diazonium ion products. 

Attempts to protonate diazocarbonyl compounds in superacids at C(l) failed (Allard et al., 1969 Wentrup and Dahn, 1970). When diazoacetone (2.10) was treated at -60 to -80°C in FSO3H - SbFs - SO2 or in HF-SbF5-S02, the O-protonated enoldiazonium ions with (Z)- and (F )-configuration (2.11 and 2.12) were detected by NMR spectroscopy. It may be that there is a hydrogen bond formed between the OH and the diazonio group in 2.11. 

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