A mixture of carbohydrazide 4 (0.196 g, 1.0 mmol) and indoline-2,3-dione derivatives 5al (1.0 mmol) in EtOH (30 mL) and AcOH (0.3 mL) was refluxed for 4 h. Crystallization of the resulting solid from EtOH/DMF gave compounds 6al, respectively.
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