Friedel-Crafts reaction Fries rearrangement

This type of duality of action is presumably present in other situations, such as the Fries rearrangement (78), the Friedel-Crafts reaction with acid chlorides (65) or acid anhydrides (21), and the catalytic chlorination of nitrobenzene (17). In these reactions it appears that the uncoordinated Lewis acid is the effective catalyst. The same situation is illustrated by recent work on aromatic amination (32, 33) and halogenation (57, 58, 71) and seems to be general feature of Lewis acid-catalyzed electrophilic reactions of aromatic compounds containing suitable donor groups. 

Reactions in this group may be divided into two categories those which may be described as Friedel-Crafts syntheses and the closely related preparations which involve a Fries rearrangement prior to a Friedel-Crafts reaction. 

Whitmore-Lux type, 21, 14, 66 Friedel-Crafts reactions, 20, 1, 29 Fries rearrangement, 21, 25 Froth dissipation, 20, 3 Fumaryl chloride, 20, 29, SI 2-Furanacrylic acid, 20, 55 Furfural, 20, 55... 

Friedel-Crafts reactions. For alkylation of arenes with secondary alkyl triflates at 80 the Sc(OTf)j catalyst can be reused without significant loss of activity. Direct acylation of 1-naphthol at C-2 and Fries rearrangement of 1-naphthyl esters are effected by... 

The Friedel-Crafts reaction and the related Fries rearrangement of aromatics are the most important methods in organic chemistry for synthesizing aromatic ketones, which are of interest in the synthesis of numerous fine chemicals such as drugs, fragrances, dyes and pesticides. 

The enones 9 are made either by a Friedel-Crafts reaction of phenols and a,P-unsaturated acid chlorides or by a Fries rearrangement of the phenol esters 10. 

Reactions of phenols and acyl chlorides in the presence of TfOH occur with 0-acylation (Friedel-Crafts acylation), while with concentrated TfOH, C-acylation (Fries rearrangement) is observed. A tandem Prins/Friedel-Crafts reaction has been reported for the construction of the indeno-tetrahydropyridine core of the haouamine alkaloids (Scheme 92). ... 

Titanium tetrachloride is a moisture-sensitive, highly flammable liquid reacting violently with water (34). It is a strong Lewis acid capable of promoting Diels-Alder reactions (35) and induces the addition of silyl enol ethers and allyl silanes to carbonyl compounds and derivatives (34r-36). It is a less commonly used catalyst in Friedel-Crafts reactions but very useful for the acylation of activated alkenes and in the Fries rearrangement. 

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