Arylation acids

RCOSH ca 1720 a,/3-Unsaturated or aryl acid or ester shifted about —25 cm ... 

UV spectra, 5, 798 synthesis, 5, 833 thermolysis, 5, 812 Tetrazole, 5-amino-2-methyl-methylation, 5, 818 Tetrazole, 2-aryl-5-substituted quatemization, 5, 815 Tetrazole, 5-aryl-acidity, 5, 816... 

Tetrazole, l-(p-substituted phenyl)-antimicrobial activity, 5, 835 Tetrazole, 5-thio-rearrangements, 5, 823 Tetrazole, 2-thioacyl-reactions, 5, 109 Tetrazole, 5-(o-tolyl)-tautomerism, 5, 804 Tetrazole, 5-(p-tolyl)-dipole moments, 5, 795 tautomerism, 5, 804 Tetrazole, 5-(trimethylsilylamino)-synthesis, 5, 832 Tefrazolecarbaldehydes reactions, 5, 820 Tetrazole-5-carbaldehydes reactions, 5, 820 Tetrazolecarbonitriles reactions, 5, 820 Tetrazole carbonyl compounds reactions, 5, 820 Tetrazolecarboxylic acid, 5-aryl-acidity, 5, 816... 

The combination Et3SiH/(C6F5)3B reduces acid chlorides to methyl groups (Eq. 138).281,282 If a smaller amount of triethylsilane is used, the same combination reduces aryl acid chlorides to the trimethylsilyl ethers of the benzyl alcohols.281,282... 

Pentaarylcyclopentadienols (375) are reported to yield endoperoxides (376) which when heated or treated with acids decompose to tetraarylfurans and the corresponding aryl acids.251 Tetraarylsubstituted cyclopentadienones such as tetracyclone (378) lead to m-diaroylstil-benes and carbon monoxide.252-255 Probably, as with other cyclopentadienes, endoperoxides are the primary products. However, no attempts seem to have been made to elucidate the mechanisms of rearrangements and decompositions involved in these reactions. 

In a similar manner, aryl acid hydrazides 150 were condensed with benzaldehydes 151 <99SC3503>. Intermediates 152 underwent cyclodehydration in the presence of polyphosphate ester (PPE) to provide phthalazines 153 in good yields. 

Strong >500 50 RC02H dimers >300 100 o-Hydroxy aryl ketones o-hy-droxy aryl acids o-hydroxy aryl esters /3-diketones tropo-lones... 

Scheme 2 shows a similar mechanistic pathway for a Heck reaction taking place on a Pd octahedral comer. This mechanism is based on that established for soluble Pd catalysts (ref. 5). Adsorption of the aryl halide (or aryl acid chloride after decarbonylation) gives the aryl Pd halide, 15, by way of the adsorbed intermediate, 14. Vinyl ether adsorption, as in 16, takes place as described in Scheme 1. Aryl insertion gives the halometalalkyl, 17, which on f) elimination to the available 4dxy orbital gives the aryl enol ether, 2 (or 1 depending on which hydrogen is eliminated in 17). The resulting halo palladium hydride, 18, then reacts with the tertiary amine to give the amine hydrochloride and regenerates the octahedral comer for further reaction.

Some support for this mechanism derives from our observation of benzyl radical from phenylacetic acid, phenoxymethyl radical from phenoxy-acetic acid, and possibly the phenyl radical from benzoic acid. Radical spectra were not found for several aryl acids with longer side chains but this is not inconsistent because the 0-phenylethyl and higher radicals are not expected to absorb strongly above 300 m/z. The case of the heterocyclics is complicated by the possibility of excitation either via the 7r-system or a lone pair electron on the heteroatom, and discussion of this group will be deferred until additional experimental data are obtained. 

Such delocalization is not possible in cyclohexanecarbonyl chloride or any other aliphatic acid chloride. For this reason, aryl acid chlorides are usually less reactive toward nucleophiles than are aliphatic acid chlorides. 

Labello NP, Bennett EM, Ferguson DM, Aldrich CC (2008) Quantitative three dimensional structure linear interaction energy model of 5 -0-[N-(salicyl)sulfamoyl]adenosine and the aryl acid adenylating enzyme MbtA. J Med Chem 51 7154-7160... 

This method is based on that of Fahim,4 who isolated 4-alkylbenzoic acids in 40-60% yields by hydrolysis of the corresponding acid chlorides. The present improved procedure includes those conditions believed to be optimum for a one-step synthesis of 4-substituted benzoyl chlorides in good yields and apparently free of positional isomers, as indicated by gas chromatography/mass spectroscopy as well as H and 13C NMR analyses. The procedure has been used successfully for the synthesis of 4-halobenzoyl chlorides and several other aryl acid chlorides,5 6 as well as for 4-alkylbenzoyl chlorides up through the decyl derivative. Some of these results are summarized in Table 1. The reaction has been run on a 1-mol scale by the submitters with no difficulty. 

C = condensation, OC = oxidative coupling, PF = phenol formaldehyde, NA = crosslinking not performed-modification was aimed at network formation, BD = bis-diazonium salts, AAC = aryl acid chlorides, CC = cyanuric chloride, NEH = normal epoxy hardeners, MEA = methacrylate. 

A variety of aromatic and vinylcarboxylic acids have also been decarboxylated an adaptations of this method involving the use of AIBN as chain initiator (equations 30 and 31). Unlike the classical Hunsdiecker reaction this variant is applicable to bodi election poor and electron rich aryl acids without the risk of electrophilic aromatic halogenation. 

Hnally, a useful, although not strictly a radical, meAod of effecting decarboxylative oxygenation is Ae so-called carboxy inversion reaction. The activated acid is transformed into a mixed all l aryl diacyl peroxide which suffers decarboxylative rearrangement to Ae alkyl ester of the aryl acid. This reaction is particularly useful as it takes place wiA retention of configuration at the migrating center (equation... 

In an analogous manner, the generation of alkyl radicals in benzene solution by the O-acyl oxime method results in the formation of alkylbenzenes with moderate to good yields for simple acids (equation 55). Use of pyridine as solvent leads to the formation of alkylpyridines as mixtures of ortho, meta and para isomers in which the para isomer predominates. The 0-acyI benzophenone oxime chemistry can also be applied to aryl acids in benzene or pyridine, resulting in the formation of mixed biaryls. A closely related method involves photolysis of mixed anhydrides of arenecarboxylic acids with the hydrox-amic acid A -hydroxy-Z-pyridone in benzene solution (equation 56). 

---