Figure 1: Brønsted base catalysts.

(a) Typical nitrogen bases used for asymmetric Brønsted base catalysis compared with chiral 3-aminopyrazolato metal complexes used in this study. (b) Examples of bifunctional chiral Brønsted base catalysts. (c) Design of chiral-at-metal octahedral IrIII complexes as bifunctional, asymmetric Brønsted base catalysts. See Supplementary Methods for the synthesis of the non-racemic chiral iridium complexes Λ-IrBB1-4.