Development of a New Dimeric Cyclophane Ligand: Application to Enhanced Diastereo- and Enantioselectivity in the Catalytic Synthesis of β-Lactams

We detail the synthesis of a new C2-symmetric
bis(cyclophane) ligand system that can be thought of as
electronically analogous to binol, but which possesses the
added “third dimension” of cyclophane chirality. The ligand
synthesis involves a spontaneous (but unexpected) atropisomerization to the desired product. We have employed this
ligand to form a metal complex that is an effective cocatalyst
for the highly enantio- and diastereoselective catalytic
asymmetric synthesis of a β-lactam.