Handbook of C-H Transformations: Applications in Organic Synthesis

Despite the fact that Friedel-Crafts (F-C) alkylation reactions are one of the oldest organic transformations requiring Lewis acids (LAs) as promoters,[1] only over the last decades significant improvements towards the design and development of new catalytic stereoselective procedures have been reported. In this scenario, two different, and in some instance complementary, approaches have been recognized to be highly effective in the enantioselective electrophilic alkylations of electron-rich aromatics: i) the use of small chiral organic molecules mimicing the catalytic activity of enzymes and ii) the employment of chiral organometallic complexes made by enantiomerally pure organic ligands (chiraphor unit) and metal salts (catalaphor unit) acting as chiral Lewis acids.