Catalytic Asymmetric Synthesis of a-Mono and a,a-Disubstituted 5-and 6-Membered a-Aza-lactams

Five- and six-membered cyclic amide structures with an embedded endocyclic alpha-aza group (alpha-aza-lactams) not only represent masked or protected forms of alpha-amino acids, but also form the core ofother medicinally relevant compound families such as (thio)hydantoins and di(tri)ketopiperazines. In recent years, catalytic methods have been discovered to synthesize these molecular scaffolds, particularly those bearing an alpha-stereogenic tri- or tetrasubstituted carbon center, enantio-selectively. The wide variety of methods and catalytic activation strategies that have been successfully applied to this end in a short period of years is notable. This short review covers the most significant, high-lighting their differences and complementarities. The methods are organized according to the disconnection approach to the target alpha-aza-lactam structure, which in most cases is deeply bound to the type ofcatalysis applied.