13832-02-5Relevant articles and documents
A new method for production of chiral 2-aryloxypropanoic acids using effective kinetic resolution of racemic 2-aryloxycarboxylic acids
Tengeiji, Atsushi,Nakata, Kenya,Ono, Keisuke,Shiina, Isamu
, p. 1227 - 1252 (2013/08/23)
We report a novel method for the preparation of 2-aryloxypropanoic acids by kinetic resolution of racemic 2-aryloxypropanoic acids using enantioselective esterification. The usage of pivalic anhydride (Piv2O) as an activating agent, bis(a-naphthyl)methanol ((α-Np)2CHOH) as an achiral alcohol, and (+)-benzotetramisole ((+)-BTM) as a chiral acyl-transfer catalyst enables the effective separation of various racemic 2-aryloxypropanoic acids to afford optically active carboxylic acids and the corresponding esters with high enantioselectivities. Furthermore, theoretical calculations of the transition states required to form the chiral esters successfully proved the enantiomer recognition mechanism of the asymmetric esterification.
PROTEASOME CHYMOTRYPSIN-LIKE INHIBITION USING PI-1833 ANALOGS
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Page/Page column 91-92, (2012/10/08)
Focused library synthesis and medicinal chemistry on an oxadiazole- isopropylamide core proteasome inhibitor provided the lead compound that strongly inhibits CT-L activity. Structure activity relationship studies indicate the amide moiety and two phenyl rings are sensitive toward synthetic modifications. Only para-substitution in the A-ring was important to maintain potent CT-L inhibitory activity. Hydrophobic residues in the A-ring?s para-position and meta-pyridyl group at the B- ring significantly improved inhibition. The meta-pyridyl moiety improved cell permeability. The length of the aliphatic chain at the para position of the A-ring is critical with propyl yielding the most potent inhibitor, whereas shorter (i.e. ethyl, methyl or hydrogen) or longer (i.e. butyl, propyl and hexyl) chains demonstrating progressively less potency. Introduction of a stereogenic center next to the ether moiety (i.e. substitution of one of the hydrogens by methyl) demonstrated chiral discrimination in proteasome CT-L activity inhibition (the S-enantiomer was 35-40 fold more potent than the R-enantiomer)
A great improvement of the enantioselectivity of lipase-catalyzed hydrolysis and esterification using co-solvents as an additive
Nishigaki, Tomohiro,Yasufuku, Yoshitaka,Murakami, Sayuri,Ebara, Yasuhito,Ueji, Shin-Ichi
experimental part, p. 617 - 622 (2009/04/11)
Addition of co-solvents such as tetrahydrofuran resulted in a great improvement of the enantioselectivity of lipase-catalyzed hydrolysis of butyl 2-(4-substituted phenoxy)propanoates in an aqueous buffer solution. On the other hand, lipase lyophilized from an aqueous solution containing the co-solvents catalyzed highly enantioselective esterification of 2-(4-substituted phenoxy)propionic acids, 2-(4-isobutylphenyl)propionic acid (ibuprofen), and 2-(6-methoxy-2-naph-thyl)propionic acid (naproxen) in an organic solvent. An increase in the E value up to two orders of magnitude was observed for some substrates. The origin of the enantioselectivity enhancement caused by the co-solvent addition was mainly attributed to a significant deceleration in the initial reaction rate for the incorrectly binding enantiomer, as compared with that for the correctly binding enantiomer. From the results of FT-1R, CD, and ESR spectra, the co-solvent addition was also found to bring about a partial destruction of the tertiary structure of lipase.
Microbial deracemization of α-substituted carboxylic acids: Substrate specificity and mechanistic investigation
Kato, Dai-Ichiro,Mitsuda, Satoshi,Ohta, Hiromichi
, p. 7234 - 7242 (2007/10/03)
A new enzymatic method for the preparation of optically active α-substituted carboxylic acids is reported. This technique is called deracemization reaction, which provides us with a route to obtain the enantiomerically pure compounds, theoretically in 100% yield starting from the racemic mixture. This means that the synthesis of a racemate is almost equal to the synthesis of the optically active compound, and this concept is entirely different from the commonly accepted one in the asymmetric synthesis. Using the growing cell system of Nocardia diaphanozonaria JCM3208, racemates of 2-aryl- and 2-aryloxypropanoic acid are deracemized smoothly and (R)-form-enriched products are recovered in high chemical yield (>50%). In addition, using optically active starting compounds and deuterated derivatives as well as inhibitors, we have disclosed the fact that a new type of enzyme takes part in this biotransformation, and that the reaction proceeds probably via the same mechanism as that in rat liver.
Flexibility of lipase brought about by solvent effects controls its enantioselectivity in organic media
Ueji, Shin-ichi,Taniguchi, Tomohiko,Okamoto, Takashi,Watanabe, Keiichi,Ebara, Yasuhito,Ohta, Hitoshi
, p. 399 - 403 (2007/10/03)
The behavior of the enantioselectivity of Candida rugosa lipase was studied in the esterification of 2-(4-substituted phenoxy)propionic acids with 1-butanol in aliphatic, aromatic, and ethereal solvents, (cyclohexane, heptane, toluene, benzene, isooctane, dibutylether, etc.). Changing the solvent from cyclohexane to tert-butyl methyl ether, the isotropic signal increased quickly and the spectral line narrowed in width. The enzyme enantioselectivity in organic solvents was mainly controlled by its flexibility. The enantioselectivity of lipase in organic solvents was closely correlated with the lipase flexibility brought about by the cooperative solvent effects rather than with a sole solvent property, e.g., dielectric constant and hydrophobicity.
Enantioselective hydrolysis of some 2-aryloxyalkanoic acid methyl esters and isosteric analogues using a penicillin G acylase-based HPLC monolithic silica column
Massolini, Gabriella,Calleri, Enrica,Lavecchia, Antonio,Loiodice, Fulvio,Lubda, Dieter,Temporini, Caterina,Fracchiolla, Giuseppe,Tortorella, Paolo,Novellino, Ettore,Caccialanza, Gabriele
, p. 535 - 542 (2007/10/03)
A technique based on liquid chromatography has been developed to facilitate studies of enantioselectivity in penicillin G acylase (PGA)-catalyzed hydrolysis of some 2-aryloxyalkanoic acid methyl esters and isosteric analogues. PGA was covalently immobilized on an aminopropyl monolithic silica support to create an immobilized HPLC-enzyme reactor. Two sets of experimental data were drawn to calculate the enantioselectivity (E) of the kinetically controlled enantiomer-differentiating reaction, the degree of substrate conversion and the enantiomeric excess of the product. The developed enzymatic reactor was coupled through a switching valve to an achiral analytical column for separation and quantitation of the hydrolysis products. The enantiomeric excess was determined off-line on a PGA-chiral stationary phase. In this way, highly precise E values were determined. A computational study related to the hydrolysis of the considered racemic esters was also carried out in order to unambiguously clarify both the substrate specificity and the enantioselectivity displayed by PGA.
