Diarylacetic acids

This procedure is especially suited for preparing variously substituted diarylmethanes.1 6 The l,l-diaryl-2,2,2-trichloro-ethanes may be converted to the corresponding benzophenones via the l,l-diaryl-2,2-dichloroethylenes7 and to 1,1 -diarylacetic acids.8... 

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]. 

Stannic chloride Diarylacetic acids from arenes Synthesis with addition of two C-atoms... 

Irradiation of 4,6-dimethyl-a-pyrone immobilized in a guanidinium-sulfonate-calixarene gives rise to a 4,6-dimethyl-Dewar-p-lactone, a carboxyl zwitterion and 1,3-dimethylcyclobutadiene, both in the solid crystalline state and in aqueous solution. Diarylmethyl carbocations have been generated within the cavities of non-protic zeolites (LiY, NaY, KY, RbY, CsY, and NaX) via laser-mediated decarboxylation of diarylacetic acids. 

Scheme 7.26 Pd-Catafyzed as3qnmetric CDC reaction between diarylacetic acid Na salt and aUcenes.

Photodecarboxylation of the dissociated form of a-hydroxy-substituted arylacetic acids and related substrates occurs from the singlet excited state (SJ and leads to the corresponding benzyl alcohols with high quantum yields (O = 0.2 to 0.7) via a heterolytic mechanism (Scheme 2). Photodecarboxylation of some diarylacetic acids (Scheme 2) also proceeds from Sj via heterolytic mechanism. It is remarkable that these compounds show dramatic differences in their relative photodecarboxylation efhciency (O = 0.04 to 0.6). The reaction is enhanced when a cyclic delocalized carbanion with 4n electrons is formed. By contrast, photodecarboxylation of m- and p-nitrophenylacetic acids in aqueous solutions occurs via a heterolytic mechanism from Tj." The photodecarboxylation of pyruvic and benzoylformic acids takes place with high quantum yields ( 5 > 0.6) in aqueous solutions, to give acetaldehyde and benzaldehyde, respectively as the primary photoproducts. On the other hand, 2-, 3-, and 4-pyridinylacetic acids undergo photodecarboxylation in aqueous solutions via a heterolytic mechanism from their zwitterionic forms. 

Sodium,potassium Carboxylic acids from ethers Diarylacetic acids... 

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