Catalytic enantioselective conjugate addition of indoles to simple α,β-unsaturated ketones

Chiral [Al(salen)Cl] complex (10 mol%) in the presence of 2,6-lutidine (10 mol%) was found to be effective in catalysing the enantioselective Friedel–Crafts-type conjugate addition of indoles (3) to (E)-arylcrotyl ketones (2), furnishing the corresponding β-indolyl ketones in excellent yield and high enantioselectivity (ee up to 89%).