Imidazolethiones: novel and efficient organocatalysts for asymmetric Friedel–Crafts alkylation

Imidazolethiones organocatalyzed the asymmetric Friedel–Crafts alkylation of pyrroles with α,β-unsaturated aldehydes was achieved to afford the corresponding adducts in moderate to good yields and good to excellent enantioselectivities. The possible mechanism was proposed.