Chiral -iron(ii) complexes with metal- and ligand-centered chirality for highly regio- and enantioselective alkylation of N-heteroaromatics.

Iron-catalyzed highly regio- and enantioselective organic transformations with generality and broad substrate scope have profound applications in modern synthetic chemistry; an example is herein described based on -Fe complexes having metal- and ligand-centered chirality. The -β Fe(N) complex [Fe(L)(OTf)] (L = ,'-bis(2,3-dihydro-1-cyclopenta-[]quinoline-5-yl)-,'-dimethylcyclohexane-1,2-diamine) is an effective chiral catalyst for highly regio- and enantioselective alkylation of N-heteroaromatics with α,β-unsaturated 2-acyl imidazoles, including asymmetric N1, C2, C3 alkylations of a broad range of indoles (34 examples) and alkylation of pyrroles and anilines (14 examples), all with high product yields (up to 98%), high enantioselectivity (up to >99% ee) and high regioselectivity. DFT calculations revealed that the "chiral-at-metal" -β configuration of the iron complex and a secondary π-π interaction are responsible for the high enantioselectivity.