C₂-Symmetric 2,2'-Bipyridine-α,α'-1-adamantyl-diol Ligand: Bulky Iron Complexes in Asymmetric Catalysis

The synthesis of a chiral 2,2'-bipyridine-α,α'-1-adamantyl-diol ligand was achieved starting from commercially available materials. The bulky ligand was synthesized in three steps in 40% overall yield with stereoselectivities of 98% de and >99.5% ee for the S,S enantiomer. The absolute configuration of and structural insights into a heptacoordinated 2,2'-bipyridine-α,α'-1-Ad-diol/Fe^II chiral complex were obtained from single-crystal diffraction analyses. The newly synthesized ligand was used in iron-catalyzed asymmetric Mukaiyama aldol, thia-Michael, and Diels-Alder reactions.