A review of new developments in the Friedel-Crafts alkylation - From green chemistry to asymmetric catalysis.
The development of efficient Friedel-Crafts alkylations of arenes and heteroarenes using only catalytic amounts of a Lewis acid has gained much attention over the last decade. The new catalytic approaches described in this review are favoured over classical Friedel-Crafts conditions as benzyl-, propargyl- and allyl alcohols, or styrenes, can be used instead of toxic benzyl halides. Additionally, only low catalyst loadings are needed to provide a wide range of products. Following a short introduction about the origin and classical definition of the Friedel-Crafts reaction, the review will describe the different environmentally benign substrates which can be applied today as an approach towards greener processes. Additionally, the first diastereoselective and enantioselective Friedel-Crafts-type alkylations will be highlighted.
Rueping
Magnus
M
Institute of Organic Chemistry, RWTH Aachen, Landoltweg 1, 52074 Aachen, Germany. Magnus.Rueping@rwth-aachen.de
Nachtsheim
Boris J
BJ