METHOD FOR PRODUCING OXINDOLES

The invention relates to a method for producing 2-oxindoles from the corresponding isatines of formula (I), wherein R can be H, CH3, phenyl or benzyl and R1 can be H, C1-C4-alkyl, C1-C4-alkoxy, phenyl phenoxy, halogen, amino, nitro or hydroxy. Said isatines are converted by means of hydrazine hydrate in a polar solvent at a temperature of 15 to 185° C. to form a corresponding isatine hydrazone which directly undergoes further reaction to form the corresponding 2-oxindole of formula (II) by adding diazabicyclooctane and/or diazabicycloundecane and/or ethyldiisopropylamine as a catalyst in temperatures of 100 to 185° C., whereby the produced reaction water is distilled off. According to formula (II), R and R1 have the aforementioned definitions. The 2-oxindole is isolated from the reaction mixture by distilling off the solvent and by means of crystallisation.