Access to α‐ and β‐Hydroxyamides and Ureas Through Metal‐Catalyzed C≡N Bond Hydration and Transfer Hydration Reactions

Abstract

Dedicated to Prof. Christian Bruneau for his outstanding contributions in homogeneous catalysis.The hydration of nitriles is an important transformation because the resulting primary amides present a huge number of applications in synthetic organic chemistry, as well as industrial and pharmaceutical interest. Metallic compounds (complexes, oxides, and nanoparticles) are known to catalyze the hydration of nitriles by activating the nitrile substrate, the water molecule, or both partners, upon coordination. In this Minireview article, the application of metal-based catalysts in the hydration of α-and β-hydroxynitriles and cyanamides is comprehensively discussed. Compared to more classical organonitriles, little attention has been paid to the hydration of these particular class of substrates despite the synthetic relevance of the respective carboxamides, i. e. α-/β-hydroxyamides and ureas. Transfer hydration strategies, in which a water surrogate is employed to convert the C�N group into the C(=O)NH 2 one, are also covered.

Contemporary Approaches for Amide Bond Formation

“…Remarkable results have been achieved through these approaches, and this manuscript will review some of the most significant findings. Additionally, there are other options available for amide bond formation, such as oxidation of CH 2 groups, CO insertion, [3] hydration of nitriles, [4] or even decarboxylation reactions (Figure 1c). These “new” options have garnered interest due to their compatibility with alternative energy sources like microwaves, mechanical forces, [5] electrochemistry, [6] or light, [7] and their adaptability to flow chemistry [8] …”