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

• DOI: 10.1039/c9sc04858h
• Publication Date: 2019-11-25T10:23:41Z
• Authors: Jinhu Wei; Bei Cao; Chun-Wai Tse; Xiao-Yong Chang; Cong-Ying Zhou; Chi-Ming Che
• Keywords: Chirality; Tsuji–Trost reaction; Quinoline; Chiral ligand; Stereocenter

Iron-catalyzed highly regio- and enantioselective organic transformations with generality broad substrate scope have profound applications in modern synthetic chemistry; an example is herein described based on cis-FeII complexes having metal- ligand-centered chirality. The cis-β FeII(N4) complex [FeII(L)(OTf)2] (L = N,N'-bis(2,3-dihydro-1H-cyclopenta-[b]quinoline-5-yl)-N,N'-dimethylcyclohexane-1,2-diamine) effective chiral catalyst for alkylation of N-heteroaromatics α,β-unsaturated 2-acyl imidazoles, including asymmetric N1, C2, C3 alkylations a range indoles (34 examples) pyrroles anilines (14 examples), all high product yields (up to 98%), enantioselectivity >99% ee) regioselectivity. DFT calculations revealed that the "chiral-at-metal" configuration iron secondary π-π interaction are responsible enantioselectivity.