Anhydrides arene Friedel-Crafts acylation

What combination of acyl chloride or acid anhydride and arene would you choose to prepare each of the following compounds by Friedel-Crafts acylation ... 

Friedel-Crafts acylations of arenes with RCOCl or anhydrides (RC—O—CR) in the presence of AICI3 give good yields of ketones. 

The reaction that occurs with arenes and acid anhydrides in the presence of aluminum chloride is Friedel-Crafts acylation. The methoxy group is the more powerful activating substituent, so acylation occurs para to it. 

In a Friedel-Crafts acylation reaction an acyl chloride or acid anhydride reacts with an arene to yield an aryl ketone. 

In the presence of a stoichiometric amount of SbCls, Friedel-Crafts acylation proceeds with acyl hahdes and acid anhydrides [47], SbCls also promotes the Fries rearrangement of phenyl acetates [48], The electrophilic acylation of fluoro-olefins with acetyl fluoride or benzoyl fluoride is promoted by SbFs in liquid SOy [49], The Friedel-Crafts acylation of benzene and electron-rich arenes is successfully catalyzed by SbCl5-AgClO4 [50], SbCl, Ar.BCl [51], SbCl5-LiClO4 [52], or CaCI, AgSbFg [53] (Scheme 14,19), Acyl chlorides, acid anhydrides, and acyl enolates are used as sources of acyl groups. 

Bismuth(lll) salts such as BiCls, BiBrj, Bi(OCOR)3, and Bi (OTf), [166] have been widely used as Lewis acid catalysts to mediate C-C bond formation. Bi (OTf) 3, Bi2O3, and BiCl, catalyze Friedel-Crafts acylation with acyl chlorides or acid anhydrides [167]. Both electron-rich and electron-deficient arenes are acylated in high yields under catalysis by Bi(OTf)3 (Scheme 14.82). Under microwave irradiation the catalytic activity of BiX3 (X = C1, OTf) in the acylation of aromatic ethers is enhanced [168]. The N-acyl group of p-substituted anilides migrates to the ortho position of the aromatic nucleus under BiCls catalysis [169]. Treatment of 2,3-dichloroanisole with the ethyl glyoxylate polymer in the presence of a catalytic amount of Bi(OTf)3 affords an a,a-diarylacetic acid ester quantitatively (Scheme 14.83) [170]. 

Friedel Crafts acylation (Section 12.7) Acyl cations (acylium ions) generated by treating an acyl chloride or acid anhydride with aluminum chloride attack aromatic rings to yield ketones. The arene must be at least as reactive as a halobenzene. Acyl cations are relatively stable, and do not rearrange. 

Late-transition metal salts have been utilized as catalysts to promote Friedel-Crafts acylation of arenes and heteroarenes with anhydrides. A mismatch between their soft metal center and the hard carbonyl oxygen atoms of the products avoids the formation of a kinetically inert complex and results in catalytic turnovers. Although late-transition metal salts exhibit, a priori, rather poor Lewis acidity, sufficient reactivity can be gained by rendering them cationic. The acylation of variously substituted... 

Ytterbium(lll) tris(perfluoroalkanesulfonyl)methides 34 are effective catalysts (10% mol) for the Friedel-Crafts acylation of arenes with anhydrides. Compounds 34 can be prepared as described in Scheme 3.7. Trimethylsilylmethyl lithium 31 is reacted with commercially available per-fluoroalkanesulfonyl fluorides, giving intermediates 32 that can similarly produce tris-perfluoroalkanesulfonyl derivatives 33. These compounds are converted into the catalysts 34 by reaction with ytterbium oxide. It is shown that the highly fluorinated catalyst (34, Ri = C5F13, = C8F17) (10% mol)... 

Thanks to their low cost and easy availability, many metal-exchanged clays have been patented as efficient solid catalysts in Friedel-Crafts acylation reactions. A great number of arylketones is prepared by electrophilic acylation of arenes with anhydrides in the presence of ion-exchanged clays at 150°C-250°C. Thus, for example, aluminum-enriched mica promotes the reaction of BAN with mcto-xylene at reflux for 4 h in 99% yield. 

Friedel-Crafts acylation. Using the AgC104-SiCl4 combination as catalyst, the acylation of arenes with free carboxylic acids and an aroic anhydride proceeds via the mixed anhydrides. 

Friedel-Crafts acylation. The catalyst combined with TfOH in MeCN is an effective promoter of arene acylation with anhydrides at room temperature (14 examples, 61-98%). 

The Friedel-Crafts acylation of arenes with acetic anhydride was efficiently catalyzed by ytterbium tris(per luoroalkanesulfonyl)methides 29a-29c [32]. Itwas demonstrated that catalyst 29c could be recovered in 96% yield by extraction of the reaction mixture with hot perfluoromethyldecalin and could be re-used in a second run. 

A slightly different type of fluorous lanthanide complex, Yb[C(S02C6Fi3)2 (S02C8Fi7)]3, showed a modest catalytic activity in BTF, but was found to be an effective catalyst in perfluoromethyldecalin for the Friedel-Crafts acylation of arenes with an acid anhydride. For example, anisole reacted with acetyl anhydride in the presence of 10mol% of the catalyst in perfluoromethyldecalin at 110°C for 2h to give the product in an 82% yield. Furthermore, the catalyst was recovered in a 96% yield via extraction of the reaction mixture with hot perfluoromethyldecalin ( 85°C). A 77% conversion was obtained in a second reaction with the recycled catalyst. 

Friedel-Crafts Reactions. Aluminum trifluoromethanesulfonate has been used for the Friedel-Crafts alkylation reaction of toluene with isopropyl and tert-butyl chlorides (eq 1), and for the acylation of benzene and toluene with acetyl and benzoyl chlorides in low to moderate yields. Intramolecular Friedel-Crafts acylation of an aromatic compound with Meldrum s acid has also been reported using catalytic amounts of Al(OTf)3. Acylation of 2-methoxynaphthalene with acetic anhydride has been reported using Al(OTf)3 and lithium perchlorate as an additive to afford the corresponding 6-acetylated adduct in 83% yield. Effective acylation of arenes with carboxylic acids has also been disclosed using polystyrene-supported Al(OTf)3. ... 

Activated Esters. Mixed anhydrides may be prepared by reaction of carboxylic acids with trifluoroacetic anhydride. The method has been used widely as a means of activating carboxyl groups to nucleophilic attack. The method has also been highly useful in Friedel-Crafts acylation of arenes (eqs 1 and 2). Sulfonic acids are also activated to nucleophilic attack substituted sulfones result. Intramolecular Friedel-Crafts reactions are also facilitated, but only for formation of six-membered rings. ... 

Acybaion. These anhydrides are powerful acylating agents. Thus nonactivated arenes such as benzene arc readily acylatcd without addition of Friedel Crafts catalysis ... 

Apart from the arene substrate and an alkyl halide or acyl halide/acid anhydride, Friedel-Crafts alkylations and acylations most often involve a Lewis acid promoter in the form of a metal halide, like AlCl. Several species may function as the active electrophile, and both acyl halide/metal halide complexes and acylium ions have been observed experimentally. The complex forming ability of these metal halides complicates all mechanistic evaluations, and Friedel-Crafts reactions have rarely been the subject of quantum chemical mechanistic studies. 

Aryl- and alkyl-carboxylic dihalophosphoric anhydrides acylate activated arenes without the need for a conventional Friedel-Crafts catalyst. The anhydrides are prepared in situ, and the low temperatures required (20 C) allow reasonable yields of ketones to be obtained from mixed anhydrides of low stability, for example those derived from acetic and pivalic acids [equation (8)]. 

Aryltrifluoromethyl ketones are prepared by reaction of an aryl-lithium with a,a,a-trifluoro-N,N-dimethylacetamide. 2-Acyloxypyridines and N-acylimidazoles, " in conjunction with trifluoroacetic acid, acylate arenes in good yield without the need for a classical Friedel-Crafts catalyst or a preformed mixed anhydride. However, imidazole in trifluoroacetic anhydride is reported to form 2-aryl-Af,JV -diacyl-4-imidazolines with arenes reactive towards electrophilic attack. These adducts are readily hydrolysed by sodium hydroxide to the corresponding aldehyde [equation (14)]. This sequence may offer advantages over the Vilsmeier method of formylation, in that the aldehyde is introduced in a protected form. 

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