A Unified Strategy for the Synthesis of Diverse Bicyclo[2.2.2]octadiene Ligands

A new approach for the enantioselective synthesis of various bicyclo[2.2.2]octadiene ligands has been developed, which features a chiral oxazaborolidinium-catalyzed asymmetric Diels-Alder reaction to construct the bicyclo[2.2.2]octane framework. The pivotal ketone <b>12</b> served as a common intermediate that was finally transformed into the desired <i>C</i>₁- and <i>C</i>₂-symmetric chiral dienes. This work provides an alternative method to the reported chiral diene synthesis and would be beneficial to exploration of the potentials of this type of versatile ligand in new asymmetric transformations.