6275-27-0Relevant academic research and scientific papers
Enantioselective hydrogenation of α-phenylcinnamic acids over cinchonidine-modified Pd/C commercial catalysts
Sato, Haruka,Mameda, Takuya,Nakai, Kengo,Misaki, Tomonori,Haruyama, Yuichi,Sonobe, Seiji,Kubota, Takeshi,Okamoto, Yasuaki,Sugimura, Takashi
, p. 31 - 45 (2016/02/20)
Enantioselective hydrogenation of α-phenylcinnamic acid (PCA) and p,p′-dimethoxyphenylcinnamic acid (DMPCA) was studied over a variety of commercial 5 % Pd/C catalysts to reveal catalyst properties suitable for obtaining high enantioselectivity. The catalysts were characterized by CO adsorption, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). It is confirmed that pretreatment at 353 K under atmospheric pressure of H2 before modification with cinchonidine is very effective for all the Pd/C catalysts used here to improve the selectivity and reaction rate. It is suggested that the distribution of Pd metal particles is crucial to attain high selectivity (ee% = 79 ± 1 for PCA, 89 ± 2 for DMPCA): a uniform or eggshell-type distribution of Pd is more suitable than an egg-white or egg-yolk-type distribution. It is also suggested that the dispersion of Pd metal particles controls the enantioselectivity over cinchonidine (CD)-modified Pd/C catalysts. XPS techniques are proposed to provide a convenient method to find desirable catalysts. The choice of such Pd/C catalysts could facilitate high-throughput guided study on highly enantioselective hydrogenation of α,β-unsaturated carboxylic acids.
GUANIDINE DERIVATIVES AS TRPC MODULATORS
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Page/Page column 43; 54, (2014/02/16)
The present invention is directed to guanidine derivatives as inhibitors of transient receptor potential canonical channels (TRPC channels), in particular TRPC3 and/or TRPC6 and/or TRPC7 activity, more particularly TRPC6 activity. Also provided herein are processes for preparing compounds described herein, intermediates used in their synthesis, pharmaceutical compositions thereof, and methods for treating or preventing diseases, conditions and/or disorders mediated by TRPC channels (Formula (I))
Anomalous ligand acceleration on cinchona-modified Pd/C during asymmetric hydrogenation of properly substituted phenylcinnamic acid
Ogawa, Hiroyuki,Mameda, Takuya,Misaki, Tomonori,Okamoto, Yasuaki,Sugimura, Takashi
, p. 813 - 815 (2013/09/02)
The hydrogenation of 4,4'-dimethoxy-α-phenylcinnamic acid over Pd/C showed a large ligand acceleration effect when a cinchonidine modifier was used; the hydrogen rate increased to 370% relative to the reaction rate on unmodified Pd/C and resulted in a 91% enantiomeric excess (ee). Another good substrate, 4-fluoro-2'-methoxyphenylcinnamic acid, also resulted in a high ee value of 92%; however, the rate increased only to 230% when this modifier was used. On the basis of the difference in the degree to which the reaction rate was accelerated, the eemax for each substrate was analyzed.
Heterogeneous enantioselective hydrogenation of hydroxy-substituted (E)-2,3-diphenylpropenoic acids over Pd/Al2O3 modified by cinchonidine
Sz?ll?si, Gyo?rgy
experimental part, p. 345 - 351 (2012/06/18)
The enantioselective hydrogenation of (E)-2,3-diphenylpropenoic acids substituted by hydroxyl group has been studied over Pd/Al2O 3 catalyst modified by cinchonidine. The effect of the acidic hydroxyl substituents was compared with that of the methoxy group in the same position. The para-hydroxyl substituent on the 3-phenyl ring had similar effect on the enantioselectivity as the methoxy group, whereas the meta positioned decreased the optical purity of the saturated acid. This was explained by different origin of the increase in the enantioselectivity obtained in the presence of electron releasing substituents in these positions. Although, the para-hydroxyl group on the 2-phenyl ring had beneficial influence on the enantioselectivity of the hydrogenation of the mono-substituted acid, in the presence of fluorine or hydroxyl group on the 3-phenyl ring the effect of the two substituents was not additive. This study demonstrated that the cinchonidine-modified Pd catalyst is appropriate for the preparation of several hydroxy-substituted 2,3-diphenylpropionic acids in good optical purities, extending the scope of this catalytic system to new types of versatile chiral building blocks.
Synthesis, cure kinetics, and physical properties of a new tricyanate ester with enhanced molecular flexibility
Guenthner, Andrew J.,Davis, Matthew C.,Lamison, Kevin R.,Yandek, Gregory R.,Cambrea, Lee R.,Groshens, Thomas J.,Baldwin, Lawrence C.,Mabry, Joseph M.
experimental part, p. 3933 - 3942 (2012/05/04)
1,2,3-Tris(4-cyanatophenyl)propane, a new tricyanate ester monomer that was designed to incorporate more flexible chemical linkages at junction points in the cured macromolecular network, was synthesized in nine steps with an overall yield of 26%. The highly purified monomer exhibited an activation energy of 110 kJ/mol for auto-catalytic cure at temperatures of 210 °C-290 °C, modestly lower than the comparably measured activation energy of a commercial cyanated novolac. The overall extent of cure achievable at these temperatures was also higher for the new monomer. Many physical properties of the cured monomer, including density, thermochemical stability, moisture uptake, and the impact of hydrolytic degradation on glass transition temperature were similar to those of commercial tricyanates, with a dry glass transition temperature at full conversion of at least 340 °C. These results illustrate how careful control of the local chemical structure in the vicinity of network junction points may be utilized to improve the properties of thermosetting polymer networks.
Estrogen receptor-β potency-selective ligands: Structure-activity relationship studies of diarylpropionitriles and their acetylene and polar analogues
Meyers,Sun,Carlson,Marriner,Katzenellenbogen,Katzenellenbogen
, p. 4230 - 4251 (2007/10/03)
Through an effort to develop novel ligands that have subtype selectivity for the estrogen receptors alpha (ERα) and beta (ERβ), we have found that 2,3-bis(hydroxyphenyl)propionitrile (DPN) acts as an agonist on both ER subtypes, but has a 70-fold higher relative binding affinity and 170-fold higher relative potency in transcription assays with ERβ than with ERα. To investigate the ERβ affinity- and potency-selective character of this DPN further, we prepared a series of DPN analogues in which both the ligand core and the aromatic rings were modified by the repositioning of phenolic hydroxy groups and by the addition of alkyl substituents and nitrile groups. We also prepared other series of DPN analogues in which the nitrile functionality was replaced with acetylene groups or polar functions, to mimic the linear geometry or polarity of the nitrile, respectively. To varying degrees, all of the analogues show preferential binding affinity for ERβ (i.e., they are ERβ affinity-selective), and many, but not all of them, are also more potent in activating transcription through ERβ than through ERα (i.e., they are ERβ potency-selective). meso-2,3-Bis(4-hydroxyphenyl)succinonitrile and dl-2,3-bis(4-hydroxyphenyl)succinonitrile are among the highest ERβ affinity-selective ligands, and they have an ERβ potency selectivity that is equivalent to that of DPN. The acetylene analogues have higher binding affinities but somewhat lower selectivities than their nitrile counterparts. The polar analogues have lower affinities, and only the fluorinated polar analogues have substantial affinity selectivities. This study suggests that, in this series of ligands, the nitrile functionality is critical to ERβ selectivity because it provides the optimal combination of linear geometry and polarity. Furthermore, the addition of a second nitrile group β to the nitrile in DPN or the addition of a methyl substitutent at an ortho position on the β-aromatic ring increases the affinity and selectivity of these compounds for ERβ. These ERβ-selective compounds may prove to be valuable tools in understanding the differences in structure and biological function of ERα and ERβ.
