A Desymmetric Dearomatization Cyclopropanation of [2.2]Paracyclophane

Chiral [2.2]paracyclophane (PCP) is an intriguing prevalent scaffold widely utilized in pi-stacked polymers, luminescent materials, and asymmetric catalysis. However, current synthetic methods to access chiral PCP derivatives are still limited to physical separation and chemical or kinetic resolution. The direct desymmetric functionalization of nonsubstituted PCP has been a challenge since its discovery 70 years ago. Herein, we present a catalytic desymmetric dearomatization cyclopropanation reaction of PCP, providing rapid access to enantioenriched PCP cyclopropyl carboxylates with continuous tertiary/quaternary/quaternary chiral centers. The application of the chiral PCPs obtained has also been demonstrated by transformation to structurally novel C 2 symmetric dirhodium catalysts. Of equal importance, detailed density functional theory calculations have been carried out to reveal the mechanism of this reaction. The key to this success is a structurally symmetric bulky C 4 dirhodium catalyst: noncovalent interactions exist between substrates and catalysts, which form a cavity to host substrates, and mainly affect the regio- and enantioselectivity.