Acetals arylacetals

Benzyl acetates. Arylacetic act Mn(OAc)j in HOAc. The intermediat. -.ectron-donating p-substituent in the a caction. 

Arylacetate esters have been generated by coupling aryl bromides with stannyl enolates generated from silyl ketene acetals. 

Selective monoalkylation of methyl aryl-acetates by alkylhalides is difficult with conventional bases. It may be achieved by application of the three-step procedure outlined above adding (33) to the methyl arylacetates at a low temperature... 

In addition, the following o-substituted arylacetic acid derivatives are suitable starting materials for the syntheses of 3(2//)-isoquinolinones o-formylphenyl-acetamides [71T4653 80JCS(P1)2013], o-cyanophenyl-acetic esters (68BSF3403), and o-cyanophenylacetic acid chlorides [68AG(E)484]. 

On the preparative side, template reactions are again useful for example, the template condensation of phthalimide (or its potassium salt) with malonic acid or arylacetic acids in the presence of zinc or cadmium acetate has been shown to result in the formation of [ML] (H2L = tetrabenzoporphyrin or maso-tetraaryltetrabenzoporphyrin).1134,1135... 

The reaction of nitroarenes with silyl end ethers and ketene silyl acetals in MeCNATiF with 1 equiv. of TASF, followed by in situ oxidation with Br2 or DDQ, provides an easy route to a-nitroaryl carbonyl compounds (Scheme l).12 The use of these compounds as reagents for the synthesis of arylacetic acids, propionic acids, indoles, 2-indolinones and other heterocyclic compounds has recently been described.88... 

Several substitution reactions are catalyzed by iron ions (Galli Bunnett 1984). A detailed preparative study was recently reported on the ferrous ion-initiated SrnI reactions of haloarenes with the sodium enolates of tcri-butyl acetate, /V-accty I morpholine and a number of higher A-acylmorpholines. Smooth and rapid substitution occurs and good to excellent yields were obtained of arylacetic esters, arylacetamides, and arylalkyl amides. The... 

The mixture of arylacetic acids is subsequently decarboxylated237 by Mn(OAc)3 to a mixture of xylyl acetates ... 

In an industrial asymmetric synthesis en route to the antiinflammatory agent naproxen, the dimethyl L-tartrate acetals of ethyl aryl ketones are brominated in high yield and selectivity to give the corresponding a-bromo derivatives. Subsequent stereospecific Ag -promoted 1,2-aryl migration provides the 2-alkyl-2-arylacetic acid after hydrolysis of the tartrate auxiliary, which is recovered (e.g. eq 4). 

ANILINES 4-Chloro-2-pbenylquliiazolme. ANNULENES Propaigyl aldehyde. ANTHRONES Pyiidene hydrochloride. APORPHINES 6-Methoxy-7-hydroxy-3,4-dihydroisoquinoliniuin methiodide. ARYLACETIC ACIDS Ceric acetate. ARYLACETYLENES n-Butylamine. Iodoethynyl(trimethyl)siIane. 

The oxidation of substituted aromatic hydrocarbons by Mn(OAc)3 in refluxing acetic acid proceeds by two competing mechanisms (a) a free radical addition of carboxymethyl radical to the nuclear ring, forming 2-arylacetic acids and (b) a benzylic hydrogen abstraction by Mn resulting in the formation of benzyl acetates. " In the presence of strong acids such as sulfuric, trichloro- or trifluoro-acetic acids, only benzylic oxidation products are readily formed at room temperature (equation 207). ... 

Tolmetin Sodium, USP. Tolmetin sodium. I-methyl-5-(p-toluoyl)pyrrule-2-acetate dihydrate sodium. McN-25.<9 (Tolectin). is an arylacetic acid derivative with a pyrrole a- the aryl group. This drug is absorbed rapidly, with a lela-tivcly short plasma half-life (I hour). It is recommended for use in the management of acute and chronic RA. It shm- similar, but le.ss frequent, adverse effects with aspirin. Il doe-not potentiate coumarin-like drugs nor alter the Mood levels of sulfonylureas or insulin. Like other drugs in this class, it inhibits prostaglandin synthetase and lowers PCE blood levels. 

For synthesis of arylacetic esters from aryl bromides and silyl ketene acetals, copper(II) fluoride is added to the reaction media besides the Pd catalyst."... 

The reaction of ceric acetate with aromatic hydrocarbons can be used for synthesis of arylacetic acids. Thus the reaction of ceric acetate with toluene in acetic anhydridc-... 

Phthalic anhydride, when used as the carbonyl component in the Peikin reaction, affords, on treatment with acetic anhydride and potassium acetate, phthalylacetic acid (15 equation 12) a-Arylacetic acids also react with aromatic aldehydes to afford a-arylcinnamic acids (Ogliaro modirication of the Pericin condensation, equation 7) this type of reaction presumably involves the formation of the mixed anhydride of phenylacetic acid and acetic acid and/or phenylacetic anhydride. This modirication is also illustrative of the equilibrium that is established between acid, acid salt and acid anhydrides under the conditions of the reaction. 

As exemplified by equation (2), the Perkin condensation of o-hydroxybenzaldehydes is an important method for the synthesis of substituted coumarins. An interesting variation on this procedure has been reported recently. Heating a mixture of o-fluorobenzaldehyde, 2-thiopheneacetic acid, acetic anhydride and triethylamine affords directly the coumarin (20 equation 13) instead of the expected cinnamic acid (21). The reaction proceeds similarly with several arylacetic acids. The reaction presumably proceeds through the cinnamic acids (21). The observed product can conceivably arise by direct nucleophilic displacement involving the carboxylate or by an elimination/addition (benzyne) mechanism. The authors note that when 2-fluorobenzaldehyde is replaced by its 2-bromo analog in this reaction, the substituted cinnamic acid (22) is the major product and the corresponding coumarin (20) is obtained only in low yield. It is suggested that since it is known that fluoride is displaced more rapidly in nucleophilic aromatic substitution reactions, while bromo aromatic compounds form benzynes more rapidly, this result is consistent with a nucleophilic displacement mechanism. 

Although acetic anhydride is often used in the Perkin reaction as the acid anhydride component, other acid anhydrides can be used in the Perkin reaction as well. Oglialoro reported that sodium phenylacetate 21 and acetic anhydride give a-phenylcinnamic acid 22. The Oglialoro modification generates a mixed anhydride in situ and is a convenient preparative method that obviates the necessity of using the arylacetic anhydride as a starting material.2... 

The decarboxylation of mixed anhydrides of malonic acids with phenyl-acetic acid is related to the decarboxylating acylation of arylacetic acids,26 of which the following is an example ... 

---