Action of Hydrazines on 2-(2-Oxindolin-3-ylidene)malononitrile, (E,Z)-Ethyl 2-cyano-2-(2-oxindolin-3-ylidene)acetate and Isatin-β-thiosemicarbazone as a Source of Spiro Indoline-pyrazole Systems

2‐(2‐Oxindolin‐3‐ylidene)malononitrile (1a) or (E,Z)‐ethyl 2‐cyano‐2‐(2‐oxindolin‐3‐ylidene)acetate (1b) or isatin‐β‐thiosemicarbazone (1c) undergoes reactions with prototype hydrazine hydrate itself and some of its simple congeners to give hydrazone derivatives bearing indoline‐2‐one moiety (2). The hydrazone derivatives (2) when heated with acetyl acetone or ethyl acetoacetate in dry pyridine afforded the spiro indoline derivatives (3a, 3b). Also, cinnoline derivative (9) is obtained by action of hydrazine hydrate on the N‐acetyl derivative of (6a). The structures of the newly synthesized compounds were evaluated by IR, 1H‐NMR spectroscopy, mass spectra and elemental analyses.