Recent Advances in Azlactone Transformations

Azlactones, also known as oxazolones, are versatile building blocks in organic synthesis due to the presence of multiple pro‐nucleophilic and electrophilic reactive sites. Recently, several elegant organo‐ and metal‐catalyzed studies have been described, allowing the stereocontrolled access to complex structures in only one or a few chemical steps. Moreover, the development of one‐pot, tandem and domino reactions greatly enhanced the azlactone scaffold potential. In this context, this review aims to cover novel methodologies, including a brief overview of oxazolones and Erlenmeyer azlactones preparation. New approaches towards classical reactions, such as dynamic kinetic resolution, cycloadditions, and conjugate additions will be presented as well as new methodologies involving photochemical and flow chemistry technology. Finally, for most studies, selected examples will be presented and mechanistic pathways and/or activating modes will be carefully discussed. Azlactones have been extensively explored due to their intrinsic reactivity, providing valuable synthetic products. The use of azlactone core, is a simple way to mask free amino acids and perform several chemical transformations. This review covers examples from the last four years, including mechanism and reactivity discussions, as well as some selected applications.