Abstract
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Condensation of 5-methylisatin 1 with thiosemicarbazide in glacial acetic acid gives 5-methylisatin-3-thiosemicarbazone 2, whereas with thiocarbohydrazide gives bis-5-methylisatin -3-thiocarbohydrazone 3. Acetylation of 2 and 3 with acetic anhydride affords 5-spiro (5′-methylisatin)-4-acetyl-2 -(acetyl-amino)-Δ2-1,3,4-thiadiazoline 4 and 5-spiro(5′-methylisatin) -4-acetyl-2-(5′-methylisatin-3′ -hydrazino)-Δ2 -1,3,4-thiadiazoline 5 respectively. Methylation of 5 with methyliodide and sodium hydride furnishes l,1′-N,N-dimethylated product 6.