• Proceedings of the PSK Conference
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• 2003.10b
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• pp.220.3-220.3
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• 2003

Enantiomers of pindolol were prepared by chromatographic method. Racemic pindolol was derivatized with S-(-)-menthyl chloroformate((-)-MCF) forming its diastereomer, R-(+)-pindolol-(-)-MCF and S-(-)-pindolol-(-)-MCF. The diastereomer mixture was then chromatographically resolved to each diastereomer. Each diastereomer was further hydrolyzed with alkali to each enantiomer quantitatively. Racemization was not occurred in this process. Pindolol enantiomers were recovered producing good yield over 30% over all process.

• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.539-542
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• 1999

The diastereoselectivity in the photocyclization of α-(o-ethylphenyl)acetophenone(1) to 1-methyl-2-phenyl-2-indanol was studied in zeolites X and Y, and compared with that in isotropic solvents. The yields of E-diastereomer at the irradiation of 1 in protic solvents were higher than those in aprotic solvents. The ratios of E-diastereomer to Z-diastereomer in zeolites X and Y were much higher than those in isotropic solvents. The E/Z ratios at the irradiation of 1 in zeolites X were also found to be dependent on the cations present. As the cation size increased from Li+ to Cs+, the ratio decreased. However, any pattern in the E/Z ratios was not found in zeolites Y. The diastereoselectivity observed in the zeolites was interpreted by the conformational restriction imposed by the cavity size. An efficient oxidation of 1 in zeolites RbX and CsX was also observed.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2777-2780
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• 2012

• Bulletin of the Korean Chemical Society
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• v.16 no.1
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• pp.12-16
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• 1995

The diastereoselectivity of addition reaction of crotylmetal reagents to cobalt-complexed acetylenic aldehydes and metal-free aldehydes was examined. The anti-diastereomer was the predominant product when the crotyl metallics were Cr, Sn, and Zr. In THF, the uncomplexed aldehydes normally gave higher anti-diastereoselectivity. However, the cobalt-complex of silicon-substituted propynals with three bulky substituents produced increased proportions of syn-diastereomer. In DMF, the selectivity shifted towards syn-isomer except in the case of dimethylphenylsilyl substituent. When tributylstannane was used in the presence of BF3 etherate, moderate syn- selectivity was observed with uncomplexed aldehydes, but only decomposed products from complexed aldehydes.

• 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%.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.737-740
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• 2011

• BMB Reports
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• v.40 no.6
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• pp.1090-1094
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• 2007

Melittin (ME), a linear 26-residue non-cell-selective antimicrobial peptide, displays strong lytic activity against bacterial and human red blood cells. To design ME analogue with improved cell selectivity, we synthesized a melittin diastereomer (ME-D) with D-amino acid in the leucine zipper sequence (Leu-6, Lue-13 and Ile-20). Compared to ME, ME-D exhibited the same or 2-fold higher antibacterial activity but 8-fold less hemolytic activity. Circular dichroism analysis revealed that ME-D has much less $\alpha$-helical content in $\alpha$-helical content in the presence of zwitterionic EYPC/cholesterol (10 : 1, w/w) liposomes compared to negatively charged EYPE/EYPG (7 : 3, w/w) liposomes. The blue shift of the fluorescence emission maximum of ME-D in zwitterionic EYPC/cholesterol (10 : 1, w/w) liposomes was much smaller than in negatively charged EYPE/EYPG (7 : 3, w/w) liposomes. These results suggested that the improvement in therapeutic index/cell selectivity of ME-D is correlated with its less permeability to zwitterionic membranes.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.15 no.2
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• pp.65-71
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• 2015

Since the secretion of specific chiral isomers in urine (or plasma) is very crucial to diagnose some inborn metabolic disorders, clinical application of dual column achiral differential method has been performed for the absolute configuration of chiral compounds. Extracted from the acidified urine with diethyl ether, carboxylic functional group of organic acid (stereoisomers of the volatile) was derivatized with (-)-menthylation or (S)-(+)-3-methyl-2-butylation and followed by O-trifluoroacylation. Each of the enantiomers was accurately separated from the library matched double column (achiral) with a retention index (I). In various inborn metabolic disease urines, absolute chirality was identified correctly in the urine (10 patients) with inborn metabolic disease (including secretion of D, L- lactic acid, D, L-3-hydroxybutyric acid, and D, L-2-hydroxyglutaric acid). In this study, we identified and isolated the volatile diastereomer as a useful diagnostic marker, this successful application to urine specimens may be useful for diagnostic classification of inherited metabolic disorders.

• Journal of the Korean Chemical Society
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• v.55 no.6
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• pp.940-951
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• 2011

Reaction of 1-methylpyrimidine-(1H,3H,5H)-2,4,6-trione (1-MBA 1) as an unsymmetrical barbituric acid with cyanogen bromide and various aldehydes in the presence of triethylamine and/or pyridine afforded diastereomeric mixtures of new class of heterocyclic stable 5-aryl-1,1'-dimethyl- and 5-aryl-3,1'-dimethyl-1H,1'H-spiro[furo[2,3-d]pyrimidine-6,5'-pyrimidine]2,2',4,4',6'(3H,3'H,5H)-pentaones which are dimeric forms of 1-methyl barbiturate at the range of $0^{\circ}C$ to room temperature. In the reaction of some aldehydes with 1-MBA and BrCN were afforded a mixture of diastereomers. Another two aldehydes such as 4-cyano- and 2-hydroxybenzaldehydes gave exclusively two diastereomers in which binded to the salt of triethylammonium hydrobromide by intermolecular H-bond in ratio of 1:1. 4-Hydroxybenzaldehyde and 2-pyridinecarbaldehyde gave exclusively one diastereomer under the same condition. Aldehydes possessing strong electron-donor were produced exclusively two geometric isomers of Knoevenagel adduct (E- and Z-isomers). The structures of compounds were deduced by $^1H$ NMR, $^{13}C$ NMR and FT-IR spectroscopy. Mechanism of the formation is discussed.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1381-1384
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• 2003