A-Phenylvaleric acid

The following acids are formed in similar manner and yield by hydrolysis of the corresponding nitriles (p. 252) a-phenylvaleric acid, m.p. 51° and a-phenyl-y-methylvaleric acid, m.p. 78-79°. 

Lithium enolates of carboxylic acids such as phenylacetic acid or of amides such as N-methyl-N-phenylvaleric acid amide 1974 are oxidized by BTSP 1949 to a-hydroxy acids, which are isolated after esterification, e.g., to 1973, or to a-hydroxyamides such as 1975 [155] (Scheme 12.43) (cf. also the formation of 3-hydroxybutyrolactam 1962). 

A subsequent detailed analysis of the permanganate oxidation of the tertiary hydrogen atom of 4-phenylvaleric acid in 2.5 M potassium hydroxide solution supports the caged radical mechanism. The reaction order is two overall, A h/ d is ca. 11.5, ring substitution has little elfect on the rate (p 0) and the oxidation proceeds with a net 30-40 % retention of optical configuration. 

Other cyclic tetrapeptides have also been isolated by Japanese workers and AM toxins I, II, and III, isolated from Alternaria mail., are extremely toxic to certain plant species (9.10). These are constructed of L- i-hydroxyisovaleric acid, L-alanine, c-amino-acrylic acid and, in AM toxin I, L-6(-amino- -( .-methoxyphenyl)-valeric acid. The phenyl residue in AM toxin II is L-t(-amino-S-phenylvaleric acid, while in AM toxin III, it is L-ol-amino-( .-hydroxyphenyl)valeric acid (Figure 2), All the AM toxins produce leaf spot, or necrosis, in apple but as might he expected slight change in substitution (R-group) on the phenyl ring radically alters the specific activity of the molecule. Both AM toxin I and III induce interveinal necrosis in the "Indo" apple cultivar, which is also highly susceptible to A. mail. at concentrations as low as 0.1 pph within 18 h after treatment. In contrast, the resistant apple cultivar "Jonathan" is only affected by 1 ppm of AM toxin I and 10 ppm of AM toxin III. 

R = Ph, R = Et) was carried out by hydrolysis in the presence of LiOOH. As a result, (R)-3-phenylvaleric acid 54 was obtained in a highly enantioenriched forra In addition, the sugar template 55 was recovered almost quantitatively. 

This compound is most easily named by treating the phenyl group as a substituent. The phenyl group is bonded to carbon-4 (or the y-carbon, in the common system of nomenclature). The parent compoimd is pentanoic acid (valeric acid in the common system). Hence the name of this compound is 4-phenylpentanoic acid or y-phenylvaleric acid. 

Fig. 8.4. Profiles of the heat effect observed for complexation reactions of y-CyD with (a) 4-phenylbutyric acid, (b) 5-phenylvaleric acid, and (c) 6-phenylhexanoic acid under comparable experimental conditions 2.7-2.9 mM y-CyD and 190-230 mM guest in the initial solutions).

II and III are identical except for the L-a-amino-5-phenylvaleric acid and L-a-amino-5-(p-hydroxyphenyl)-valeric acid residues, respectively (Fig. 8). While all the AM toxins produce leaf spot and necrosis in susceptible apple varieties, as does the pathogen, even resistant varieties appear not to be immune to the toxin. For example, Indo which is very vulnerable to l. mali is also affected by toxins I and... 

Deuterio compounds. -Ethyl-) -(3-thianaphthenyl) propionic acid heated on a steam bath with 10 parts Ni,Al-alloy and 10 parts Na-methoxide in deuterium oxide a-ethyl-y,d,d-trideuterio-y-phenylvaleric acid. Y 70-95%. F. e., also non-... 

A further modification of the amino acid L-phenylalanine to which reference should be made is the structure 3,4-dihydroxy-2,2-dimethyl-5-phenylvaleric acid (104) which occurs in the cyclic polyester antibiotic neoantimycin from Streptoverticillium... 

Because PHAs are polymers composed of chiral building blocks, hydrolysis of PHAs leads to the release of the chiral monomers, which are valuable starting material for the synthesis of pharmaceuticals and specialty chemicals. An efficient method has been reported for the production of enantiomerically pure (R)-(-)-hydroxyalkanoic acids by in vivo depolymerization of PHAs (Lee et al. 1999c). Those (R)-(-)-3-hydroxyalkanoic acids of 4—12 carbon atoms and (R)-(-)-3-hydroxy-5-phenylvaleric acid were prepared by providing the environmental condition under which cells possess a high activity of intracellular PHA depolymerase and a low activity of a key enzyme that could convert the chiral monomer into another compound. Monomer (R)-(-)-3-hydroxybutyric acid could be produced at a high yield in 30 min by in vivo depolymerization of poly(3HB) accumulated in Alcaligenes latus. 

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