Hydratropic acid

Hydratropa-aldehyd, n. hydratropaldehyde. -alkohol, m. hydratropic aleohol. -s ure, /. hydratropic acid. 

By this method, for example, the absolute configurations of the following compounds were established (-)-2-phenylbutyric acid,[48] (-)-hydratropic acid,[48] (+)-0-acetyl-mandelic acid,t48] (-)-2-(7/-carbazolyl)propionic acid,t48] (+)-1 -phenylethanol,[48] (-)-menthol,t48] (+)-1 -phenylethylamine,[48] and 1-alanine ethylester.[48] The determination of the absolute configuration of bacteriochlorophylles c, d and e was made possible by the esterification of the phaeophorbides by CDI to imidazolides.[49]... 

Triethylamine (8) Ethanamine, N,N-diethyl- (9) (121-44-8) (R)-(+)-a-Methoxy-a-(trifluoromethyl)phenylacetic acid Hydratropic acid, p,p,p-trifluoro-a-methoxy-, (+)- (9) (20445-31-2)... 

The class of a-aryloxy hydratropic acid derivatives (see Table 4) combines the characteristics of the clofibrate and the halofenate structure. Surprisingly, this slight modification of the basic structure caused a striking increase in activity. Compound 47, structurally most closely related to clofibrate, showed a spectrum of activity, which was superior to that of clofibrate (factor 5—10). Impressive also was the higher activity of compound 53 against Su-13.437 2. The advantage of compounds 48-52 was similarly clear. Several representatives selected from this series were prepared for a clinical trial. 

Hydratropic acid Benzeneacetic acid, a-methyl- Malonic acid Propanedioic acid... 

Among the different synthetic procedures available for the preparation of hydratropic acids (e.g., indirect methylation of arylacetic acids,4 asymmetric hydroformylation of styrenes,5 rearrangements of a-bromoalkyl aryl ketals,6 etc.), direct methylation of arylacetic acid derivatives seems the most attractive from both economical and synthetic aspects the reagents are easily accessible and a one-pot reaction is involved. Nevertheless, this procedure is seldom used since the yields of the monomethyl derivatives are severely limited by the low selectivity of the reaction. Sizeable amounts of dimethylated by-products form.2 Even under phase-transfer catalysis conditions, high selectivity in monomethylation is elusive.7-8... 

A common way to generate a chiral catalyst involves a modification of Wilkinson s catalyst (340) in which an optically active tertiary phosphine, bis- or tris-phosphines are used as ligands in place of triphenyl-phosphine. If the phosphorous atom of the added phosphine is the stereogenic center, the optical yields are usually 4-22%, as in the conversion of atropic acid (447) to hydratropic acid (448) with 22% ee." " " An example of this type of phosphine is (-)-methylpropylphenylphosphine. bis(Phosphines) are commonly used, including 449 (called dipamp)" " and 450 (called R-camp)." " ... 

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