Lithiation of N′-(2-bromoaryl)-N,N-dimethylureas with methyllithium and tert-butyllithium under nitrogen in anhydrous THF at 0 °C gave doubly lithiated arylurea derivatives, which react with carbon monoxide at 0 °C to give isatins in good yields. The scope of the reaction has been demonstrated by application to the synthesis of isatin itself and four substituted isatins bearing alkyl, chloro or fluoro groups.
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