• Archives of Pharmacal Research
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• v.29 no.1
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• pp.108-111
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• 2006

The economic and effective method for preparation of R-(-)-ibuprofen by diastereomer crystallization was developed. R-(-)-ibuprofen was resolved from racemic ibuprofen by forming R-(-)ibuprofen-R-(+)-$\alpha$-methylbenzylamine diastereomeric salt with R-(+)-$\alpha$-methylbenzylamine and crystallization. The purity of R-(-)-ibuprofen-R-(+)-$\alpha$-methylbenzylamine diastereomeric salt was tested and confirmed using HPLC and $^1H-NMR$ method. The pure diastereomeric salt collected from repeated recrystallization was further fractionated by liquid-liquid extraction to the pure enantiomer without racemization. R-(-)-ibuprofen was recovered producing overall yield of 2.4% with the purity more than 99.97%.

• KSBB Journal
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• v.9 no.3
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• pp.306-311
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• 1994

Optical resolution of racemic ${\alpha}$-methylbenzylamine was carried out by using Bacillus licheniformis protease in organic media. Enantioselective amidation of racemic amino with an ester as an acyl donor was successfully employed to resolve the racemate. To enhance reaction rate and enantioselectivity, pH-adjustment by lyophilization of enzyme dissolved in buffer, colyophilization with salts or lyoprotectants, selection of solvents and molecular design of esters were investigated. The optimization of the resolution reaction achieved about 30-fold increase in initial reaction rate and about 12-fold increase in enantioselectivity, respectively.

• YAKHAK HOEJI
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• v.39 no.4
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• pp.433-437
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• 1995

Optically pure(-)-and (+)-$\alpha$-hydroxy-$\alpha$-(p-chlorobiphenyl)acetic acids were prepared. The racemate was synthesized through three steps. By condensation of p-cnorobiphenyl with diethyl ketomalonate in the presence of SnCl$_{4}$, diethyl $\alpha$-hydroxy-$\alpha$-(p-chlorobiphenyl)malonate (1) was formed and subsequently ($\pm$)-$\alpha$-hydroxy-$\alpha$-(p-chlorobiphenyl)acetic acid (3) was obtained through hydrolysis and decarboxylation. For the separation of the racemate the classical resolution method, derivatization of a racemate by reaction with an optically pure compound was employed. In this case the optically pure compound were [R]-(+)-$\alpha$-methylbenzylamine and [S]-(-)-$\alpha$-methylbenzylamine. Diastereomeric salts between acids and bases could be easily separated by crystallization in absolute ethanol.

• Journal of Applied Biological Chemistry
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• v.43 no.2
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• pp.101-103
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• 2000

The synthesis and resolution of ($\pm$)-10,11-dihydroxydibenzosuberenone 3, a potential pharmaceutical compound, is described. It was synthesized from the 5H-dibenzo[a,d]cycloheptene-5-one (dibenzosuberenone) 1, and converted to diastereomeric isomers using (R)-(+)-$\alpha$-methylbenzylamine. Optical resolution of ($\pm$)-10,11-dihydroxydibenzosuberenone 3 was possible by fractional recrystallization of the diastereomer formed in ethanol. The optical resolution of 10,11-dihydroxydibenzosuberenone through formation of its phosphoamidates 5 using the (R)-(+)-$\alpha$-methylbenzylamine was achieved. These compounds provided the optical rotation of [${\alpha}]=-64.3$ for (-)-10,11-dihydroxy-dibenzosuberenone and [${\alpha}]=+61.3$ for (+)-10,11-dihydroxydibenzosuberenone. The (-)- and (+)-enantiomers were prepared in five steps from dibenzosuberenone with overall yields of 11.66% and 9.38%, respectively.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.223.3-224
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• 2003

Chiral discrimination of ibuprofen by $^1$H-NMR using several chiral solvating agents such as (-)-brucine, (-)-cinchonidine, (1R, 2S)-(-)-ephedrine, (S)-(-)-${\alpha}$- methylbenzylamine, (-)-strychnine and L-(-)-tryptophane was investigated. Racemic ibuprofen treated with one equivalent of chiral solvating agent was preferentially crystallized. Chiral purity of each precipitates was measured by chiral HPLC and chemical shift differences(ΔΔ$\delta$) was calculated. Eventhough (S)-(-)-${\alpha}$-methylbenzylamine was most effective for the preferential recrystalization of (S)-(+)-ibuprofen, chemical shift differentiation ability was weak. (omitted)

• YAKHAK HOEJI
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• v.41 no.1
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• pp.18-21
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• 1997

Synthesis of an optically active azabicyclo[3.2.1]octane skeleton as a backbone of the tropane alkaloids has been achieved by employing intramolecular Mannich reaction. Utilizat ion of (R)-${\alpha}$-methylbenzylamine as a chiral auxiliary provided an excellent cyclization of amino dioxolane precursor. However, this auxiliary did not afford high asymmertic induction for the preparation of the optically active cyclization precursor.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.219.1-219.1
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• 2003

$^1$H-NMR method for the determination of enantiomeric purity of (S)-(+)-ibuprofen was developed using (-)-cinchonidine as a chiral solvating agent. (S)-(+)-ibuprofen was prepared by optical resolution of racemic ibuprofen using preferential recrystallization method with (S)-(-)-${\alpha}$-methylbenzylamine and (R)-(-)-ibuprofen by semi-preparative chiral HPLC using chiral OD column and n-hexane/2-propanol/trifluoroacetic acid as a mobile phase. Several concentrations of synthetic mixture of (S)-(+)-ibuprofen and (R)-(-)-ibuprofen were added to the (-)-cinchonidine disolved in CDCl$_3$. (omitted)