Buchwald heteroaryl amines

In 1995, Buchwald and Hartwig independently discovered the direct Pd-catalyzed C—N bond formation of aryl halides with amines in the presence of stoichiometric amount of base [93, 94], This field is becoming rapidly mature and many reviews covering the scope and limitations of this animation have been published since 1995 [95-102]. In the context of heteroaryl synthesis, one example is given to showcase the utility and mechanism of this reaction. Applications to individual heterocycles may be found in their respective chapters. 

Buchwald and co-workers reported that the combination of air stable Cul (instead of the air sensitive CuOTf) and racemic trans-1,2-cyclohexanediamine (ligand la), in the presence of K3PO4, K2CO3, CS2CO3, or f-BuONa comprises an extremely efficient and general catalyst for the iV-amidation of aryl and heteroaryl halides (eq 9) and the Ai-arylation of a number of heterocycles (eq 10). This approach tolerates functional groups such as primary or secondary amides, free OH or NH on the aryl halides, which were problematic with the Pd-catalyzed amination methodology. 

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