Asymmetric Construction of γ-lactams Displaying All-carbon, Aza-, Thia- and Oxa-quaternary Chiral Centers

gamma-lactams, bearing one or more chiral centers are important scaffolds and widely occur in many natural and synthetic products of clinical interest, but the synthetic approaches mainly focus on the preparation of rings that display trisubstituted carbons, whereas only a few examples concern the construction of chiral gamma-lactams that display tetrasubstituted carbon atoms. However, in recent years, the broad potential of these latter compounds was recognized and deserved high interest, owing to their complex three-dimensional features and structural rigidity. Thus, several efforts were engaged in the pursuit of new synthetic strategies towards gamma-lactam rings that contain tetrasubstituted carbons that pose a particular challenge, and the present review gathers advances reported since 2015 about the enantioselective preparation of these molecules, carried out to exploit both internal and external asymmetric induction.