Advances in Metal-Free Transamidation: A Sustainable Approach to Amide Bond Formation.

The amide functionalities are a crucial functional group in organic synthesis, playing a vital role in many processes that are essential for the efficient synthesis of important pharmaceutical and industrial compounds. Despite being one of the most commonly conducted reactions by researchers in both academia and industry, the synthesis of amides remains a staple in chemical research and development. Transamidation reactions enable the one-pot conversion of one type of amide into another. Additionally, this process is crucial in the complete synthesis of specific naturally-occurring compounds. However, these methods have certain limitations such as using toxic and corrosive starting materials, usage of strong acid or base, and metal mediated reaction, which can lead to excessive hydrolysis of the desired amide product. To overcome these challenges, more practical and efficient approaches have been developed. Metal-free transamidation reactions have emerged as a powerful and versatile synthetic methodology in organic chemistry, allowing for the direct conversion of amides into new amide products without relying on metal catalysts. In the review article, we have focused on various metal-free transamidation protocols of unactivated amides.