New strategies in organic catalysis: the first enantioselective organocatalytic Friedel-Crafts alkylation.

The metal-catalyzed addition of aromatic substrates to electron deficient σand π-systems, commonly known as Friedel-Crafts alkylation,1 has long been established as a powerful strategy for C-C bond formation.2 Surprisingly, however, relatively few asymmetric catalytic protocols have been reported that exploit this venerable reaction manifold,3 despite the widespread availability of electron-rich aromatics and the chemical utility of the accompanying products. In our recent studies, we reported that the LUMO-lowering activation of R,â-unsaturated aldehydes via the reversible formation of iminium ions with chiral imidazolidinone 14 is a valuable platform for the development of enantioselective organocatalytic Diels-Alder reactions5 (eq 1) and [3 + 2] nitrone cycloadditions6 (eq 2). In this communication, we