Heteroarylidene-tethered bis(oxazoline) copper complexes catalyzed cascade reaction involving asymmetric Friedel-Crafts alkylation/N-hemiacetalization of indoles with β,γ-unsaturated α-ketoester

A convenient approach to the synthetically and biologically useful indole derivatives was developed. A cascade sequence involving Friedel-Crafts alkylation of 3-methyl indoles with β,γ-unsaturated α-ketoester followed by N-hemiacetalization were realized using heteroarylidene-tethered bis(oxazoline)-copper complexes. The pyrroloindole products with two chiral centers were obtained in high yields (85-95%) with both high diastereoselectivities (87:13-96:4 drs) and enantioselectivities (87-98% ees). A plausible mechanism was proposed.