In asymmetric reactions catalyzed by chiral metal complexes, the ligand plays a definitive role in cooperation with the central metal. The introduction of new chiral ligands often revolutionizes the catalytic performance in terms of reactivity, selectivity, and productivity. The chiral bidentate sp~2-N-ligands that possess a privileged bipyridine-, bisoxazoline-, or diimine-skeleton have enabled the development of vast numbers of asymmetric reactions. We have designed a novel ligand, naphtho1,2-b:7,8-b'dipyrroloimidazole (Naph-diPIM), which has the following characteristics: 1) high rigidity and planarity with fixation of two sp~2-hybridized N atoms on the same side, 2) near 90° bite angle, making the coordination plane and Naph-diPIM plane coplanar to stabilize square-planar and octahedral metal complexes, 3) an extended π-conjugated system showing pyridine-level π-acceptability, and 4) high σ-donicity derived from the two amidine units. Introduction of sub-stituents on the pyrrolo moieties, such as C_2 chiral (S,S)- or (R,R)-Naph-diPIM-dioxo-R (R = iPr, Me, H) (1a-c), should create a well-defined chiral environment (see below).
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