Modular Synthesis of α-Quaternary Chiral β-Lactams via Three-Component Asymmetric Kinugasa/Aldol or Kinugasa/Mannich Cascade Reactions.

The β-lactam scaffolds are the prevalent structural units in antibiotics and natural products. Herein, three-component asymmetric Kinugasa/aldol and Kinugasa/Mannich cascade reactions have been developed for constructing α-quaternary chiral β-lactams. This method involved the tandem reaction of alkynes, nitrones and aldehydes (or imines), resulting in the formation of three sequential stereocenters controlled by copper(I) catalysts and chiral bis(oxazolidine) ligands. The developed protocol features high enantioselectivity, good reaction efficiency, and mild operational conditions, representing a practical and sustainable synthetic tool for the construction of functionalized chiral β-lactams.