Stereoselective synthesis of β-lactams: recent examples.

The synthesis of β-lactam derivatives is a research topic of great interest due to the biological activity of these molecules. Indeed, there are several antibiotics which include a β-lactam core in their structures, such as penicilins, monobactams, carbacephems and cephamycins. The development of stereoselective approaches to access these molecular architectures turns out to be necessary in order to take advantage of the distinct properties provided by the different stereoisomers. This review covers recent advances towards the stereoselective synthesis of β-lactams, including Staudinger syntheses, cascade reactions, metal-catalyzed syntheses and base-promoted cyclizations. Within these methods, some particularly novel synthetic approaches are highlighted, such as the induction of chirality through bimetallic synergistic catalysis or the transfer of chirality between components in mechanically interlocked molecules. Additionally, a critical opinion on the state of the art of this research field is offered, remarking key points on which the future research should be focused on.