Aryllactic acid

The a-keto acids are extremely versatile intermediates. For example, reduction of an arylpyruvic acid 450 yields the corresponding p-aryllactic acid 451, condensation of 450 with amines followed by reduction affords amino acid derivatives 454, ° and condensation of 450 with hydroxylamine yields a-oximi-noacids 452 as shown in Scheme 7.149. ... 

Nitrilase 11-Catalyzed Production of Aryllactic Acid Derivatives and Analogues Under DKR Conditions... 

Early workers [103] detected benzilic acid formed during the reduction of benzophenone in dimethylformamide in the presence of carbon dioxide. The carbon dioxide radical anion system is known to have E" = —2.2V (vs. SCE) [104] and will thus not be formed in preference to the ketone radical anion. Reaction occurs through trapping of aromatic carbonyl radical anions by carbon dioxide, and this has been developed into a convenient synthesis of aryllactic acids. The modern technological process uses constant current conditions. On a small scale, a divided cell with mercury cathode has been used to obtain benzilic acids from substituted benzophenones and carbon dioxide in 70-90% yields [105] and to convert 4-isopropylacetophenone to the corresponding phenyllactic acid in 85% yield [106]. On a technical scale, these reactions are best carried out in an undivided cell using a lead cathode and a sacrificial aluminum anode with dimethylformamide as solvent... 

More curiously, N-tosylated phenylalanine derivatives [10] and phenyllactic acid [11] can also be converted into 2-phenylnaphthalene in moderate yields whereas 3,4-dimethoxyphenyllactic acid treated with boron tribromide gives Kagan s ether in almost the same yield as 3,4-dimethoxyphenylethanal does [11]. In these cases, the decomposition of aryllactic acid or alanine derivatives may give arylethanal with the formation of water and carbon monoxide, Fig. (4). 

In connection with our interest in the synthesis of salvianolic acids [22,23], we needed aryllactic acids that are usually obtained by zinc amalgam reduction in boiling hydrochloric acid [39], Serendipitously, we isolated, along with the expected arylllactic acids, 2-hydroxyfuran-2-ones,... 

Figure 122. Model for the assignment of the configuration of (7 -O-aryllactic acid amides.

In most cases, only the Ad values for one substituent (either Li or L2) are reported. All the O-aryllactic acids described have the (i -configuration (i.e., they are prepared from (5)-ethyl lactate) and examples of the application of both enantiomers of the reagent to one enantiomer of the amine have not been... 

Table 12. Selected Values for (/ )-0-Aryllactic Acid Amides...

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