Azo-, diazo-, and azido-pyrazoles

Becher has discovered that 5-azido-4-iminomethylpyrazoles (185) isomerize into 5-amino-4-cyanopyrazoles (186) via ring opening/ring closure and has succeeded in isolating the open-chain intermediate (a diazadiene) 91TL3565 . 

Molina has used the double azide (187 X = N3) to prepare rigid bicyclic guanidines through the double iminophosphorane (187 X = N—PPh3) 93JOCi687 . Pyrazole-5-diazonium chloride has been transformed into the corresponding chlorosulfonyl derivative 94JHC93 . 

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