Halides, aryl reaction with amines, benzyne mechanism

Unactivated aryl halides can be converted to amines by the use of NaNH2, NaNHR, or NaNR2. With these reagents, the benzyne mechanism generally operates, so cine substitution is often found. Ring closure has been effected by this type of reaction,for example. 

The scope of this reaction appeared to be limited to dialkylamides and electron-neutral aryl halides. For example, nitro-, acyl-, methoxy-, and dimethylamino-substituted aryl halides gave poor yields upon palladium-catalyzed reaction with tributyltin diethylamide. Further, aryl bromides were the only aryl halides to give any reaction product. Vinyl bromides gave modest yields of enamines in some cases. Only unhindered dialkyl tin amides gave substantial amounts of amination product. The mechanism did not appear to involve radicals or benzyne intermediates. 

NaNHR, or NaNR2. Lithium dialkylamides also react with aryl halides to give the A-arylamine. With these reagents, the benzyne mechanism generally operates, so cine substitution is often found. The reaction of an amine, an aryl halide, and potassium tert-butoxide generates the A -aryl amine. A -Arylation was accomplished with butyllithium and a secondary amine using Ni/C-diphenylpho-sphinoferrocene (dppf). Ring closure has been effected by this type of reaction, as in the conversion of 16 to the tetrahydroquinoline. 

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