Isatin tosylhydrazones

Attempts to prepare 2-diazo-3-oxindole failed. In fact, base decomposition of the isatin-2-tosylhydrazone under conventional conditions with potassium hydroxide at room temperature led to the potassium salt (64JOC3577). When an aqueous solution of the potassium salt was heated at 70°C, indigo blue was obtained in 62% yield. 

Heating of isatin azines gave compounds of the type 95 (R = Treatment of l-methylisatin-3-tosylhydrazone with sodium in... 

Moriconi, E.J. and Murray, J.J., Pyrolysis and photoysis of l-methyl-3-diazooxidole. Base decomposition of isatin-2-tosylhydrazone, /. Org. Chem., 29. 3577, 1964. 

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