Ba black sheep: We have developed novel barium/binol catalysts prepared from alkaline earth metal amides and chiral binaphthol ligands. These catalysts effectively promoted the asymmetric Friedel–Crafts–typealkylationreactions of indoles with chalconederivatives. This is the first example of asymmetric Friedel–Crafts–typealkylationreactionsusingchiral Brønsted bases.
Synthesis of Novel Chiral Phosphoric Acid-Bearing Two Acidic Phenolic Hydroxyl Groups and its Catalytic Evaluation for Enantioselective Friedel-Crafts Alkylation of Indoles and Enones
A novel chiral phosphoric acid catalyst bearing two acidic phenolic hydroxyl groups was synthesized. Its catalytic activity as a chiral Brøsted acid has been examined in the enantioselective Friedel‐Crafts alkylation of indoles and enones as a model reaction. In comparison with the other chiral phosphoric acid catalysts, the reaction catalyzed by the novel chiral catalyst afforded the desired 3‐substituted
Chiral Brønsted acid catalyzed asymmetric Friedel–Crafts alkylation reaction of indoles with α,β-unsaturated ketones: short access to optically active 2- and 3-substituted indole derivatives
The asymmetric Friedel–Crafts alkylation reaction of indoles with α,β-unsaturated ketones catalyzed by chiral phosphoric acid is reported. A wide range of indoles and 4,7-dihydroindoles were allowed to react with α,β-unsaturated ketones to give the corresponding 1,4-adducts in good to high chemical yields and with excellent enantioselectivities.