Copper heterocyclic boronic acid

This conversion employs a boronic acid with a copper(ll) catalyst. The method was developed for reactions of heterocycles, including the V-arylation of isatin ° and of pyrazole, imidazole and their benzo derivatives (1,2,3-triazole, 1,2,4-triazole and 5-phenyltetrazole gave only very modest yields). These conditions also apply to the V-arylation of 2-pyridone (and various fused derivatives), 3-pyridazinones, indole-2-carboxylates and pyrrole-2-carboxylates. ... 

The authors of this chapter hypothesized that the first step of the reaction mechanism of the catalytic N-arylation of heterocycles with boronic acids involves rapid co-ordination/ligand exchange and dissolution of copper(ii) acetate by the substrate, such as imidazole, to form the complex 31 (Scheme 5.33). This is because cupric acetate is completely insoluble in CH2CI2 (colorless solution), the preferred solvent. When imidazole is added, the solution instantly turns deep blue, suggesting that co-... 

A very mild copper-catalyzed vinylation of amines, which involved the use of advantageous vinyl boronic acids at room temperature, was developed by Lam (Scheme 21) [89]. They proved that a combination of Cu(OAc)2 and pyridine A-oxide was an efficient catalyst system for the coupling of tra/w-1-hexenyl boronic acid with certain amines. In this respect, not only A-heterocycles such as benzimidazole and indazole but also numerous ureas and lactams underwent the cross-coupling under similar conditions. 

The last chapter by Monnier and Taillefer focuses on the copper-catalyzed formation of C(sp )-N bond via the coupling of nitrogen nucleophiles (N-heterocycles, amines, anilines, amides, ammonia, azides, hydroxylamines, nitrites salts, phosphonic amides) with aryl halides. The authors also present C (aryl)-N bond formation as a result of the coupling between these nucleophiles and aryl-boronic acids (the Chan-Lam reaction). 

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