Strain and Chirality: Catalytic Asymmetric Synthesis of Planar Chiral [2.2]Paracyclophanes

Abstract

Planar-chiral [2.2]paracyclophanes occupy a distinctive position in modern chemistry because their rigid cofacial aromatic architecture connects molecular shape, through-space electronic communication and chirality within a compact scaffold. These features have made them valuable in asymmetric catalysis, ligand and organocatalyst design, optoelectronic materials and chiroptical systems. However, the preparation of enantioenriched [2.2]paracyclophanes has historically relied on resolution-based approaches, limiting both efficiency and structural diversification. Catalytic asymmetric synthesis has recently opened new opportunities for the direct construction of planar chirality in [2.2]paracyclophane frameworks, particularly through desymmetrization of prochiral substrates. This Review summarizes recent progress in the catalytic asymmetric synthesis of planar-chiral [2.2]paracyclophanes, discusses the key structural and mechanistic features underlying enantioinduction, and outlines future directions for this rapidly evolving field. Particular attention is given to how substrate topology, catalyst design and reaction pathway govern stereocontrol, and to how the resulting enantioenriched scaffolds can serve as functional building blocks for catalysis, molecular design and chiral materials.