• Bulletin of the Korean Chemical Society
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• 제23권3호
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• pp.365-366
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• 2002

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.291-295
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• 2011

The catalytic enantioselective conjugate addition reaction of $\alpha$-nitroacetate to $\alpha,\beta$-unsaturated enones promoted by chiral bifunctional organocatalysts is described. The treatment of $\alpha$-nitroacetate to $\alpha,\beta$-unsaturated enones afforded the corresponding Michael adducts with high enantioselectivity. The conjugate addition adducts are easily converted to chiral $\gamma$-nitro ketones and $\delta$-keto esters.

• 한국환경농학회지
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• 제15권1호
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• pp.37-45
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• 1996

수도재배환경(水稻栽培環境) 및 현탁배양세포(懸濁培養細胞) 조건에서 생성된 PCP의 수용성대사물(水溶性代謝物)을 확인에 필요한 정보를 확보하기 위해서 이를 여러 chromatography로 충분히 정제한 다음 이것의 aglycons과 glycon(전보(前報)에서 ${\beta}-glucose$ conjugates인 것으로 추정)을 GC/MS로 분석, 동정하였다. Glycon, 즉 대사물의 polar부위(endocon)가 glucose임을 확인하므로써 전보에서 효소특이성을 통해 추론한 것을 입증할 수 있었다. 또한 conjugates의 source에 따라 다르기는 하였지만 배양세포에서의 aglycon(exocon)s는 주로 PCP, tetrachlorophenol이성체 및 tetra chlorocatechol을, 그리고 수도재배환경에서는 이 외에도 2,4,5- 및 2,4,6-trichlorophenol을 각각 확인할 수 있었다. 이러한 사실은 PCP glucose conjugates의 구조는 PCP뿐만 아니라 이것의 대사물인 Polychlorinated phenols가 개별적으로 glucose와 ${\beta}-anomeric$ conjugation을 이루고 있는 것으로 판단할 수 있었다. 그리고, 대사초기에 이미 여러 종류의 aglycon이 생성되는 것으로 보아 PCP자체도 빠르게 PCPs로 전환되는 것을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제18권10호
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• pp.1043-1045
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• 1997

• Bulletin of the Korean Chemical Society
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• 제13권5호
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• pp.466-467
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• 1992

• Bulletin of the Korean Chemical Society
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• 제9권4호
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• pp.269-270
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• 1988

• Journal of Microbiology and Biotechnology
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• 제20권10호
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• pp.1424-1429
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• 2010

A poly(${\gamma}$-glutamic acid) (${\gamma}$PGA)-cholesterol conjugate was synthesized and its properties were then evaluated. The conjugate exhibited an amphiphilic nature derived from the hydrophilic ${\gamma}$PGA backbone and the hydrophobic cholesterol side chain. The conjugate spontaneously formed nanoparticles, becoming an aqueous solution when at low concentrations, and at high concentrations the result was the formation of a physical gel. By utilizing the self-aggregating properties of the conjugate in water, an artificial chaperone was developed. A complex of protein, with the nanoparticles of the conjugate, was formed and the protein was released upon the dissociation of the nanoparticles through the addition of ${\beta}$-cyclodextrin. For denatured carbonic anhydrase, the activity was recovered in the artificial chaperone of the nanoparticle conjugate.

• Archives of Pharmacal Research
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• 제29권10호
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• pp.840-844
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• 2006

For the exploration of pharmacophoric moiety of malloapelta B (1) possessing the inhibitory activity of $NF-{\kappa}B$ activation, structural variation of ${\alpha},{\beta}-unsaturated$ carbonyl motif was attempted. 1 was reduced by catalytic hydrogenation, sodium borohydride, and lithium aluminumhydride. Catalytic hydrogenation with 30 psi or 15 psi of $H_2$ gas of 1 generated 8-butyl-5,7-dimethoxy-2,2-dimethylchroman (2) and 1-(5,7-dimethoxy-2,2-dimethylchroman-8-yl)butan-1-one (3), respectively. Reduction with sodium borohydride occurred at the double bond of ${\alpha},{\beta}-unsaturated$ ketone of 1 to give 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)butan-1-one (4). Reduction of 1 with lithium aluminumhydride and then quenched with methanol and water produced unexpected products, 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-3-methoxy-1-butene (5) and 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-3-hydroxy-1-butene (6). These are formed from the isomerization of initial product 9 through the continuous conjugate carbocation intermediate 11. Addition of ethylmagnesium bromide and dimethyl malonate anion to 1 gave the conjugate adducts 7 and 8. Ethylmagesium bromide and sodium borohydride reduction unusually gave the conjugate addition due to steric congestion around carbonyl group of 1. Compound 2 exhibits the reduced inhibitory activity against $NF-{\kappa}B$ activation and the others do not show the activity. Therefore ${\alpha},{\beta}-unsaturated$ carbonyl group of 1 should be important for its inhibitory activity.

• Bulletin of the Korean Chemical Society
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• 제7권6호
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• pp.425-428
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• 1986

A new heterocuprate containing 2-pyridyloxy ligand, lithium 2-pyridyloxy-n-butylcuprate, has shown improved thermal stability and it reacts with acid chlorides to afford the corresponding ketones in high yields. Similarly, it can be effectively utilized in conjugate addition reactions of $\alpha,\beta$-unsaturated ketones. Of synthetic significance is that the complete utilization of n-butyl group in lithium 2-pyridyloxy-n-butylcuprate has been observed.

• 생약학회지
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• 제17권1호
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• pp.67-72
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• 1986

A stereospecific synthesis of 3-methyl-5-(1-hydroxy-4-oxo-2,6,6-trimethyl-2-cyclohexen-1-yl)-cis, trans-2,4-pentadienoic acid (abscisic acid) from ${\alpha}-ionone$ has been investigated. Ethyl 5-(2,6,6-trimetyl-2-cyclohexen-1-yl)-trans-4-penten-2-ynoate $({\alpha},{\beta}-acetylenic\;ester)$, which was synthesized from alpha-ionone in two steps, was stereospecifically converted in good yield into ethyl 3-methyl-5-(2,6,6-trimethyl-2-cyclohexen-1-yl)-cis, trans-2, 4-pentadienoate $({\alpha}-ionylideneacetate)$ by the conjugate addition of lithium dimethylcuprate at $-78^{\circ}C$. Basic hydrolysis of the ethyl ${\alpha}-ionylideneacetate$ gave an abscisic acid precursor, 3-methyl-5-(2,6,6-trimethyl-2-cyclohexen-1-yl)-cis, trans-2,4-pentadienoic acid, which can be oxidized to yield abscisic acid.