Friedel-Crafts electrophiles

If CH2C12/A1C13 is used as electrophile in the Friedel-Crafts alkylation, a benzyl chloride is first produced. However, this compound is itself a Friedel-Crafts electrophile, and, in the presence of A1C13, it benzylates unconsumed starting material immediately. As a result, one has linked two aromatic rings with a CH2 group ... [Pg.228]

The second takes place if the organic halide contains aromatic rings this is a classical Friedel-Crafts electrophilic substitution, e.g. ... [Pg.172]

Finally, there is also a relevant example of an intermolecular conjugate Friedel-Crafts/electrophilic amination cascade developed very recently by Melchiorre in which 2-methyl-IH-indole reacted with a variety of a,p-unsatu-rated aldehydes and dialkyl azodicarboxylates in the presence of a primary amine catalyst, leading to the formation of a family of products containing two contiguous stereocenters, one of them a quaternary one (Scheme 7.43). This reaction started with the conjugate addition of 2-methyl-lH-indole to the enal... [Pg.282]

Scheme 7.43 Cascade conjugate Friedel-Crafts/electrophilic amination using a,P-disubstituted aldehydes.

The mechanism of each of the reactions in the synthesis of phenol from benzene and propene via cumene hydroperoxide requires some comment. The first reaction is a familiar one. The isopropyl cation generated by the reaction of propene with the acid (H3PO4) alkylates benzene in a typical Friedel-Crafts electrophilic aromatic substitution ... [Pg.948]

Acetylation of chlorobenzene under the same conditions affords p-chloroacetophenone with even higher selectivity (p m=99.5 0.5). Acetylation of hromohenzene and fluorobenzene afford the para isomers exclusively. The para meta and para.ortho selectivities exhibited hy AcCl/AlCls are greater than those exhibited by most other Friedel-Crafts electrophiles. [Pg.8]

Friedel-Crafts electrophiles do not attack strongly deactivated benzene rings... [Pg.715]

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