Friedel-Crafts reaction with acyl chlorides

The ex- and y-silylaled allylphosphonates, prepared by the carbanionic silylation of allyl- and vinylphosphonates and a subsequent double bond migration, undergo the Friedel-Crafts reaction with acyl chlorides in ClhCl, al room temperature in the presence of AlCljto give high yields of... 

Two new methods of formation of C-C bond at C-2 of glycals, with retention of the glycal double bond, have been published recently. Vilsmeier-Hack reaction is involved in the formylation of glycals [180], A Friedel-Crafts reaction of acyl chlorides with glycals, in the presence of aluminium chloride, is required for the C-2 acylation of glycals (Scheme 49) [181]. 

Highly enantiosele ctive annulation reactions of (tert-butyldiphenylsilyl)allenes with ethyl glyoxylate using bis(oxazolinyl)pyridine-scandium triflate complex was described [120]. This [3 + 2] cycloaddition gave the corresponding dihydrofurans in moderate to high yields with high enantioselectivities (Scheme 12.54). The vinyl-silane functionality was acylated in Friedel-Crafts reaction with acetyl chloride to produce a-alkoxyenone. 

Sometimes acylium ions lose carbon monoxide to generate an ordinary carbonium ion. It will be recalled that free acyl radicals exhibit similar behavior at high temperatures. Whether or not the loss of carbon monoxide takes place seems to depend on the stability of the resulting carbonium ion and on the speed with which the acylium ion is removed by competing reactions. Thus no decarbonylation is observed in Friedel-Crafts reactions of benzoyl chloride, the phenyl cation being rather unstable. But attempts to make pivaloyl benzene by the Friedel-Crafts reaction produce tert-butyl benzene instead. With compound XLIV cyclization competes with decarbonylation, but this competition is not successful in the case of compound XLV in which the ring is deactivated.263... 

Friedel became internationally known for the synthetic method called the Friedel-Crafts Reaction using aluminum chloride as a catalyst in the the introduction of an alkyl or acyl group into benzene. James Mason Crafts was an American professor from MIT working with Friedel in 1877 at the Sorbonne. Crafts later became president of MIT. 

Diketones have been prepared by the Friedel-Crafts method. Both acyl chloride groups in adipyl chloride react with benzene in the presence of aluminum chloride to form the diketo compound, 1,4-dibenzoylbutane (81%). When diketene is treated with benzene under the conditions of the Friedel-Crafts reaction, benzoylacetone, COCHjCOCH, is formed... 

Benzothiazolones (121) undergo Friedel-Crafts acylation through the reaction with acyl chlorides or anhydrides in the presence of a large excess (7-11 equivalents) of the AICI3-DMF reagent (Equation (21)). The same 6-acyl-2-(3//)-benzothiazolones (122) are obtained from (121) and anhydrides in the presence of polyphosphoric acid <94J0C1574>. 

The thus established stereocenter served in the following steps. Conversion of 50 to 51 was achieved by acyl chloride formation followed by Friedel-Crafts reaction with ethylene and A1C13. Addition of the lithium enolate of t-butylacetate occurred from the less-hindered face of the cyclic ketone to give, after reduction and tosylation, adduct 52. Tosylate displacement with amine 53, esterification with methoxyacetylchloride, and addition of HC1 gave mibefradil 54. 

Optically pure (R)-2-chloropropionic acid (90) is available by diazotization of L-alanine in 6n HCl [31]. Using the corresponding acid chloride 91 as an acylating agent, Friedel-Crafts reaction with isobutylbenzene produces aryl ketone 92 with an enantiomeric purity of 85%. 

Cariwxylic Acid Derivatives.— The anion generated by treatment of (pentafluoro-phenyl)acetonitrile with sodium hydride in 1,2-dimethoxyethane (DME) effects nucleophilic substitution in polyfiuoroarenes to give diarylacetonitriles (123 X = F, CFs, H, Br, Cl, Me, or COaEt) - hydrolysis of the first five of these yields the related acids (124), the first two of which undergo conventional acid-catalysed est ification or conversion into acyl chlorides. Some Friedel-Crafts reactions of bispentafiuorophenylacetyl chloride are also shown in Scheme 30 (the ketone CeFs-CHPh-COPh has been made by a similar sequence starting from PhCHa-... 

As already pointed out in Chapter 6 (shown as the seventh item in Table 6.12 and described in Scheme 6.88), acyl halides undergo the Friedel-Crafts reaction with aromatic systems in the presence of aluminum trichloride (AICI3). Thus, ethanoyl chloride (acetyl chloride, CH3COCI) reacts with benzene under these conditions... 

TTie true ketones, in which the >CO group is in the side chain, the most common examples being acetophenone or methyl phenyl ketone, C HjCOCH, and benzophenone or diphenyl ketone, C HjCOC(Hj. These ketones are usually prepared by a modification of the Friedel-Crafts reaction, an aromatic hydrocarbon being treated with an acyl chloride (either aliphatic or aromatic) in the presence of aluminium chloride. Thus benzene reacts with acetyl chloride... 

As shown in the sixth entry of Table 24 4 C acylation of phenols is observed under the customary conditions of the Friedel-Crafts reaction (treatment with an acyl chloride or acid anhydride m the presence of aluminum chloride) In the absence of aluminum chloride however O acylation occurs instead... 

Sulfonylation. Under Friedel-Crafts reaction conditions, sulfonyl haUdes and sulfonic acid anhydrides sulfonylate aromatics (139), a reaction that can be considered the analogue of the related acylation with acyl haUdes and anhydrides. The products are sulfones. Sulfonyl chlorides are the most frequently used reagents, although the bromides and fluorides also react ... 

Several methods are available to supplement the phenol alkylations described above. Primary alkylphenols can be produced using the more traditional Friedel-Crafts reaction. Thus an -butylphenol can be synthesized direcdy from a butyl haUde, phenol, and mild Lewis acid catalyst. Alternatively, butyryl chloride can be used to acylate phenol producing a butyrophenone. Reduction with hydrazine (a Wolff-Kishner reduction) generates butylphenol. 

Another important use of BCl is as a Ftiedel-Crafts catalyst ia various polymerisation, alkylation, and acylation reactions, and ia other organic syntheses (see Friedel-Crafts reaction). Examples include conversion of cyclophosphasenes to polymers (81,82) polymerisation of olefins such as ethylene (75,83—88) graft polymerisation of vinyl chloride and isobutylene (89) stereospecific polymerisation of propylene (90) copolymerisation of isobutylene and styrene (91,92), and other unsaturated aromatics with maleic anhydride (93) polymerisation of norhornene (94), butadiene (95) preparation of electrically conducting epoxy resins (96), and polymers containing B and N (97) and selective demethylation of methoxy groups ortho to OH groups (98). 

One of the most useful reactions of acyl chlorides was presented in Section 12.7. Friedel-Crafts acylation of aromatic rings takes place when arenes are treated with acyl chlorides in the presence of aluminum chloride. 

The syntheses of 1 utilized the Ullmann ether synthesis.13 Reaction of 2 mol of 1-bromonaphthalene with 4,4-(hexafluoroisopropylidiene)diphenol afforded the desired product 1. The reaction was carried out in DM Ac at 160°C in the presence of potassium carbonate as the base and copper (I) iodine as the reaction catalyst to yield 1, as depicted in Scheme 1. The reaction proceeded slowly but in good yield with easy isolation of the desired compound. Acylation of 1 with 4-fluorobenzoyl chloride to prepare 2 was carried out under modified Friedel-Crafts reaction conditions14 using dimethyl-sulfone as catalyst moderator. Both 1 and 2 were easily recrystallized to yield high-purity monomers suitable for polymerizations. 

Friedeb Crafts reaction Anisole undergoes Friedel-Crafts reaction, i.e., the all rl and acyl groups are introduced at ortho and para positions by reaction with alkyl halide and acyl halide in the presence of anhydrous alurntnlurn chloride (a Lewis acid) as catalyst. 

Friedel-Crafts reactions in the ionic liquid system l-methyl-3-ethylimidazolium chlo-ride-aluminium(ni) chloride can be performed with excellent yields and selectivities, and in the case of anthracene, have been found to be reversible. This ionic liquid has been shown to demonstrate catalytic activity in reactions such as Friedel-Crafts acylations (Surette et al., 1996 Boon et al., 1986) alkylation reactions (Koch et al., 1976),... 

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