Halides, aryl reaction with potassium phthalimide

The reaction with ammonia or amines, which undoubtedly proceeds by the SNAr mechanism, is catalyzed by copper8" and nickel105 salts, though these are normally used only with rather unreactive halides.106 This reaction, with phase transfer catalysis, has been used to synthesize triarylamines.107 Copper ion catalysts (especially cuprous oxide or iodide) also permit the Gabriel synthesis (0-58) to be applied to aromatic substrates. Aryl bromides or iodides are refluxed with potassium phthalimide and Cu 0 or Cul in dimethylacetamide to give N-aryl phthalimides, which can be hydrolyzed to primary aryl amines.108... 

Gabriel reaction. Review.1 The Gabriel reaction is ordinarily not applicable to aryl halides however, under catalysis with cuprous bromide or iodide and in boiling DMA (dimethylacetamide) as solvent, aryl bromides or iodides (but not chlorides) react with potassium phthalimide to give phthalimido compounds in >5-95% yield.2... 

The Gabriel synthesis of amines uses potassium phthalimide (prepared from the reaction of phthalimide with potassium hydroxide). The structure and preparation of potassium phthalimide is shown in Figure 13-13. The extensive conjugation (resonance) makes the ion very stable. An example of the Gabriel synthesis is in Figure 13-14. (The N2H4 reactant is hydrazine.) The Gabriel synthesis employs an 8, 2 mechanism, so it works best on primary alkyl halides and less well on secondary alkyl halides. It doesn t work on tertiary alkyl halides or aryl halides. 

A new method of synthesis of A-alkylphthalimides (79) via alkylation of phthalim-ide in dry media under microwave irradiation was carried out by Bodgal et al. (1996). The reactions were performed by simply mixing phthalimide with an alkyl halide adsorbed on potassium carbonate to give a good yield of the product. Yadav and Subba Reddy (2000) reported a novel and efficient synthesis of A-arylamines (80) by the reaction of activated aryl halides with secondary amines in the presence of... 

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