Direct Catalytic Amidations from Carboxylic Acid and Ester Derivatives: A Review

The prevalence of amides in biological systems and chemical fields such as polymers, materials and natural products drives continuous research on novel procedures to obtain these ubiquitous functional groups. Currently, efforts to this purpose are mainly focused around the discovery of direct and catalytic methods that are more atom economic, safe and practical for diversified applications (e.g., organic, medicinal and peptide chemistries, material and polymer purposes, etc.), in accordance with green chemistry principles. The field of amide synthesis has attained such a level of significance that the number of reviews and articles addressing it grown exponentially in the last decade. Rather than providing a general overview of amidation methods, which have been described broadly and well in recent literature, the purpose of this review is to highlight recent efforts in the catalytic formation of amide bonds from amines and carboxylic acids or esters. The goal is to emphasize mechanistic and catalytic aspects, but also to discuss substrate tolerance and racemization issues (when applicable)