106319-23-7

Upstream product

• 4314-68-5 3-(4-methoxyphenyl)-2-phenylpropionic acid 
• 6968-77-0 2-phenyl-3-p-methoxyphenylacrylic acid 
• 103-82-2 phenylacetic acid 
• 123-11-5 4-methoxy-benzaldehyde 
• 6968-77-0 3-(4-methoxyphenyl)-2-phenylacrylic acid 
• 22979-35-7 Methyl phenyldiazoacetate 
• 104-93-8 p-methylanizole 

Downstream Products

• 178258-43-0 (R)-3-(4-Hydroxy-phenyl)-2-phenyl-propionic acid 

Relevant academic research and scientific papers

The effect of the substrate structure on the stereoselectivity in an asymmetric hydrogenation of unsaturated carboxylic acids over cinchonidine-modified palladium catalyst

An enantiomeric ratio of 10:1 (82% ee) was achieved for the first time in the hydrogenation of α,β-unsaturated acids with heterogeneous catalysts by designing the substrate structure to enhance the interaction with the catalyst, and to increase the intrinsic stereoselectivity.

Surface enhanced Raman spectroscopic (SERS) behavior of substituted propenoic acids used in heterogeneous catalytic asymmetric hydrogenation

The strength and geometry of adsorption of substituted propenoic acids on silver surface were studied by means of surface enhanced Raman spectroscopy (SERS) using silver sol. Based on their SERS behavior, two classes of phenylpropenoic acids studied were distinguished. The first class of propenoic acids (atropic acid, (E)-2,3-diphenylpropenoic acid, (E)-2-(2-methoxyphenyl)-3-phenylpropenoic acid, (E)-2,3-di-(4-methoxyphenyl)phenylpropenoic acid and (E)-2-(2-methoxyphenyl)-3-(4-fluorophenyl)propenoic acid) has shown strong charge transfer (CT) effect. We suggest bidentate carboxyl bonded species based on the SERS enhanced bands of νCOO- around 1394 cm-1 and νC-C of the -C-COO- moiety at 951 cm-1. In these series the plane of the α-phenyl group (γCH out-of-plane vibrations at 850-700 cm-1) is almost parallel to the silver surface, while the β-phenyl group is in tilted position depending on the type and the position of substituent(s) showing strong SERS enhanced bands of νCC + βCH (in-plane mode) at 1075 cm-1, νCC (ring breathing mode, in-plane) at 1000 cm-1 and γCCC (out-of-plane mode) around 401 cm-1. The other class of propenoic acids (cinnamic acid, (E)-2-phenyl-3-(4-methoxyphenyl)propenoic acid) has shown weak electromagnetic (EM) enhancement (CC bands is enhanced in cinnamic acid). In this case no significant carboxyl enhancement was observed, so we suggest that adsorbed species lie parallel to the surface. The two types of adsorption can be related to the dissociation ability of the carboxylic group. In the first case the carboxylic H dissociates, while in the second case it does not, as indicated also by the characteristic νCO band at 1686 cm-1 in the FT-Raman spectra of methanolic solutions.

Enantioselective hydrogenation of α,β-unsaturated carboxylic acid over cinchonidine-modified Pd nanoparticles confined in carbon nanotubes

We report the enantioselective hydrogenation of α,β-unsaturated acid catalyzed by Pd nanoparticles in carbon nanotubes (CNTs) taking the advantage of the channels as nanoreactors. The Pd nanocatalyst inside the channels of CNTs shows higher activity and e

Enantioselective iridium-catalyzed hydrogenation of α-arylcinnamic acids and synthesis of (S)-equol

By using iridium catalyst based on chiral spiro phosphine-oxazoline ligands, the hydrogenation of α-arylcinnamic acids was accomplished under ambient pressure and low catalyst loading (as low as 0.01 mol %), providing useful 2,3-diarylpropionic acids in high yields with excellent enantioselectivities (up to 99% ee). A catalytic enantioselective synthesis of (S)-equol with the present hydrogenation reaction as a key step was accomplished starting from commercially available starting materials in six steps with 48.4% overall yield.

Cinchona methyl ethers as modifiers in the enantioselective hydrogenation of (E)-2,3-diphenylpropenoic acids over Pd catalyst

The enantioselective hydrogenation of (E)-2,3-diphenylpropenoic acids over Pd/Al2O3 modified by (R)C8(S)C9 cinchona ethers resulted in the inversion of the sense of the enantioselectivity. To find the explanation of the phenomenon, the interaction of acids bearing different substituents with cinchona alkaloids was studied in solution by NMR spectroscopy and experiments using mixtures of modifiers were carried out. The prominent non-linear behaviour obtained revealed the altered adsorption of the cinchona methyl ethers when compared with the parent alkaloids. The investigations indicated that the interaction of the ether derivatives with the unsaturated acids is more flexible and the presence of the methyl group reshapes the chiral surface sites. The combination of these effects complemented by the bulkiness of the diaryl substituted acrylic acids may lead to the inversion of the docking preference of the substrates in the altered chiral pocket of the adsorbed modifier and consequently results in decrease in the enantioselectivity or even in the inversion of its sense. Novel evidence on the ligand-accelerated mechanism in the enantioselective hydrogenation of (E)-2,3-diphenylpropenoic acids over cinchona alkaloid-modified Pd in the presence of benzylamine was also presented.

Up to 96% enantioselectivities in the hydrogenation of fluorine substituted (E)-2,3-diphenylpropenoic acids over cinchonidine-modified palladium catalyst

The enantioselective hydrogenation of methoxy-and fluorine-substituted (E)-2,3-diphenylpropenoic acid derivatives was studied over cinchonidine- modified, supported palladium catalysts in the absence and presence of benzylamine as additive. The fluorine substituent in the appropriate position was even more efficient than the methoxy group in increasing the optical purity of the saturated product. High enantioselectivities, up to 96%, were obtained in the hydrogenation of some disubstituted derivatives, unprecedented in the hydrogenation of prochiral unsaturated carboxylic acids over modified heterogeneous catalyst. The best optical purities were reached in the hydrogenation of derivates bearing a para-substituent on the β phenyl and an ortho-substituent on the a phenyl ring, respectively. The influence of the substituent on the β phenyl ring was attributed to the increase in the efficiency of the modifier-substrate interaction by electronic effects or to a decrease in the adsorption strength of the substituted acid over modified surface sites. The beneficial effect of the ortho-substituent on the a phenyl ring was assumed to be due to the additional interaction of this substituent with the modifier on the surface, its steric hindrance contributing only in a small part to the observed effect. These suggestions were supported by results obtained in the hydrogenations of some methyl-substituted derivatives.

Intermolecular C-H activation at benzylic positions: Synthesis of (+)-imperanene and (-)-α-conidendrin

An efficient C-H activation of primary benzylic positions by means of rhodium carbenoid induced C-H insertions is described. This key step was used in concise syntheses of (+)-imperanene and (-)-α-conidendrin.

Deracemization of α-substituted arylacetic acids

Reaction of rac-α-substituted arylacetyl chlorides with (R)- and (S)-3-hydroxy-4,4-dimethyl-1-phenyl-2-pyrrolidinone under standard esterification conditions, gave esters (3R,αR)- and (3S,αS)-3, respectively, with a diastereoselectivity which diminishes on increasing the steric effect of the α-substituent. Controlled acidic hydrolysis of esters 3 afforded the corresponding acids 4 with minimal racemization. Boron tribromide demethylation of (R)- and (S)-4d gave without racemization the hydroxyacids (R)- and (S)-4e, known precursors of (R)- and (S)-iodoalphionic acid.