3-Phenyllactic acid

Phenyl-jodidchlorid, n. phenyl iodochloride, -milchsaure, /. phenyllactic acid, -saure, /. phenylic acid (phenol, CeHaOH). -schwefel-saure, /. phenylsulfuric acid, -senfol, n. phenyl mustard oil. -siliciumchlorid, n. trichlorophenylsilane, CaHiSiCla. -verbindung, /. phenyl compound, -wasserstoff, m. phenyl hydride, benzene. 

Two reactions for the production of L-phenylalanine that can be performed particularly well in an enzyme membrane reactor (EMR) are shown in reaction 5 and 6. The recently discovered enzyme phenylalanine dehydrogenase plays an important role. As can be seen, the reactions are coenzyme dependent and the production of L-phenylalanine is by reductive animation of phenylpyruvic add. Electrons can be transported from formic add to phenylpyruvic add so that two substrates have to be used formic add and an a-keto add phenylpyruvic add (reaction 5). Also electrons can be transported from an a-hydroxy add to form phenylpyruvic add which can be aminated so that only one substrate has to be used a-hydroxy acid phenyllactic acid (reaction 6). 

The following chemicals were obtained commercially (Sigma Chemical Co.) and bioassayed with C. album and Amaranthus retroflexus L. (seeds collected in North Carolina in 1980) following identification DL-3-hydroxybutyric acid (DL-3-hydroxy-butyric acid as a Na salt) and L-3-phenyllactic acid (L-2-hydroxy-3-phenyl-propanoic acid). 

Figure 3. The effect of DL-B-hydroxybutyric acid ( HBA) and L-g-phenyllactic acid (BPLA) on C. album hypocotyl length (HL).

In eq. [20] the chemical correlation between (S)-( — )-phenyllactic acid (known absolute configuration) and (- )-epoxychalcone is shown. 

Phenyllactic acid is converted to the (S)-( - )-hydroxyketone via its ester and amide. Reduction of the (- )-epoxychalcone yields the ( + )-rotating a-hydroxyketone. Therefore the configuration of the a-carbon of the epoxy-chalcone must be R. Since epoxychalcones are derived from /rans-chalcones, the configuration of the (3-carbon in the epoxychalcone must be 5, as shown in Figure 12. 

Strom et al have isolated a Lactobacillusplantarum strain (MiLAB 393) with antifungal properties from grass silage. Three antifungal substances produced by the strain have been isolated, that is, cyclo(Phe-Pro), cyclo(Phe- w j-4-OH-Pro), and 3-phenyllactic acid. 

In the tricyclic inhibitor series amidation of benzhydryl ester 81b with phenyllactic acid or mono-ferf-butyl /i-benzylsuccinate gives 395 (92EPP481522) and 396 (95USP5455242), respectively. A similar amidation... 

Table II. Correlation coefficients between growth parameters affected by a-phenyllactic acid and, p-ethoxybenzoic acid in the light...

Subject Phenylacetic Acid Mandelic Acid o-Hydroxy- phenylacetic Acid Phenyllactic Acid Phenyl- pyruvic Acid p-Hydroxy- phenylacetic Acid... 

Note that we have used the following notation for hydroxy acids in this section, -O-Gly for the glycolic acid residue -0CH2C(0)-, likewise -O-Ile is the isoleucic acid residue -OCH(CHMeEt)C(0)-, -O-Leu is the leucic acid residue -0CH(iBu)C(0)-, -O-Phe is the (3-phenyllactic acid residue -0CH(Bzl)C(0)-, and -O-Phg is the phenylglycolic acid residue -OCHPhC(O)-. 

Smidt and Langner111"1 in their synthesis of the natural calcium blocker leualacin utilized the Mitsunobu reaction for the construction of the linear depsipeptide N-(tert-but oxycarbony I) -(3-alanyl-O-D-leucic acid benzyl ester in 69% yield. Higher yields (94-96%) were reported for two didepsipeptide units N-(/er/-butoxycarbonyl)-./V-methylleucyl-D-lactic acid diphen-ylmethyl ester and iV-(/er/-butoxycarbonyl)-yV-methylleucyl-D-phenyllactic acid diphe-nylmethyl ester in the course of the total synthesis of the anthelmintic cyclooctadepsipeptide PF1022A based on the Mitsunobu reaction.1102 ... 

The phosphonate g, prepared from L-B-phenyllactic acid and the phosphonochloridate gg, binds to CPA equally as tightly as does the more labile phosphonamidate 2. 

In order to extend the two-enzyme system to other 2-hydroxy acids, a racemase with a broader activity was found in Lactobacillus paracasei. This was exploited for deracemization of 2-hydroxy-4-phenylbutanoic acid and 3-phenyllactic acid, which are important synthetic intermediates. In addition, in this case the procedure requires a kinetic resolution step and a successive racemization step. O-Acetyl derivatives of the absolute (S)-configuration can be obtained in two successive repeating cycles. Yields are around 60%. Of course the 0-acetyl derivatives of opposite configuration can be obtained when the lipase-catalyzed reaction is apphed in the hydrolysis direction. Obtaining the O-acetyl derivatives of the absolute (R)-configuration requires an additional acetylation step of the initially resolved and racemized (S)-hydroxy acid [12]. 

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