Synthesis of 3‑Indolylglycine Derivatives via Dinuclear Zinc Catalytic Asymmetric Friedel–Crafts Alkylation Reaction

A direct asymmetric Friedel–Crafts (F–C) alkylation reaction between a wide range of indoles and ethyl 2-(4-methoxyphenylimino)­acetate catalyzed by Trost’s dinuclear complex is reported. A series of 3-indolylglycine derivatives were synthesized in enantioselectivity of up to >99% enantiomeric excess (ee) using 10 mol% catalyst loading under mild conditions. This atom economic reaction could be run on a gram scale without impacting its enantioselectivity. The absolute stereochemistry of catalytic products was determined by correlation with a known configuration compound. A possible mechanism was proposed for the asymmetric induction.