• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.47-50
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• 2008

The diastereoselectivity of Diels-Alder reactions were studied on the silica surface supported with different concentrations of cerium ion as efficient Lewis acid catalysts under solvent-free conditions. The results showed that the diastereoselectivity of reaction was highly improved in these conditions. The cerium ion was grafted on silica surface by using ion exchange method.

• Bulletin of the Korean Chemical Society
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• v.28 no.7
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• pp.1156-1158
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• 2007

Valerophenone shows a dramatic shift of photoreactivity by a cyclopropyl group at alpha position to the carbonyl group. By the minor change of structure, the diastereoselectivity of the Yang photocyclization is reversed and the ratio of cyclization to elimination products increases significantly.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.325-328
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• 1999

In the reactions of the enolates of various 2-piperidineacetates with iodomethane or trisyl azide, the anti isomer was always predominant over the syn one, independent of the stereochemistry of the piperidineacetates. The piperidineacetates having OTBDMS moiety at C5 proceeded more diastereoselectively than the compounds without the substituent. The diastereoselectivity could be explained by perpendicular model for the electrophilic substitution reaction.

• 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.

• Bulletin of the Korean Chemical Society
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• v.23 no.5
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• pp.665-666
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• 2002

• Journal of the Korean Chemical Society
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• v.39 no.6
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• pp.431-433
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• 1995

• Bulletin of the Korean Chemical Society
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• v.18 no.2
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• pp.141-142
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• 1997

• Bulletin of the Korean Chemical Society
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• v.19 no.3
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• pp.378-379
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• 1998

• 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.27 no.5
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• pp.783-785
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• 2006