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Asymmetric [2,3]-Wittig Rearrangements in the Presence of Sparteine Derivatives
Jahyo Kang,Won Oh Cho,Hyung Geun Cho,Hee Jin Oh Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.9
Asymmetric [2,3]-Wittig rearrangements of allyl propargyl ethers in hexane were performed in the presence of s-butyllithium and (-)-${\alpha}$-isosparteine which is a $C_2$-symmetric chiral ligand for the alkyllithium reagent. The reactions of (Z)-or (E)-allyl 3-trimethylsilylpropargyl ethers at -78$^{\circ}C$ showed good diastereoselectivities (74-100%) and moderate enantioselectivities (29-71%). The absolute configurations of the rearrangement products were determined by the corresponding Mosher's esters. It was found that (-)-${\alpha}$ -isosparteine induced (R) configuration at the hydroxy carbon and syn stereochemistry more favorably. The possible transition state is discussed.
A Shapiro Reaction with N,N-Diethylaminosulfonylhydrazones
Kang Jahyo,Kim, Ji Han,Jang Gil-Seong Korean Chemical Society 1992 Bulletin of the Korean Chemical Society Vol.13 No.2
A modified Shapiro reaction was developed using N,N-diethylaminosulfonylhydrazones.
Selective Reduction of Keto Esters with Zinc Borohydride
윤능민,강재효,Nung Min Yoon,Jahyo Kang Korean Chemical Society 1975 대한화학회지 Vol.19 No.5
대표적 케토에스테르를 수소화붕소아연으로 선택환원하여 해당하는 히드록시에스테르 또는 락톤을 좋은 수득률로 합성하였다. Selective reduction of carbonyl group with zinc borohydride in the presence of ester functional group was demonstrated with seven representative keto esters. Either hydroxy esters or lactones were obtained in good yields; ethyl 6-hydroxyheptanoate ($83.0{\%}$), ethyl 2,6-dimethyl-4-hydroxy-2-cyclohexenecarboxylate ($82.3{\%}$), ethyl p-(${\alpha}$-hydroxyethyl)-phenylacetate ($78.9 {\%}$), 4-phenylbutyrolactone ($70.2{\%}$), and 3-phenylphthalide ($92.4{\%}$) were obtained from the corresponding keto esters.
Selective Reduction of <TX>${\alpha},\;[\beta}$-Epoxy Ketones with Zinc Borohydride
윤능민,강재효,Nung Min Yoon,Jahyo Kang Korean Chemical Society 1975 대한화학회지 Vol.19 No.5
에폭시케톤을 수소화붕소 아연으로 환원하면 카르보닐기만 선택적으로 확원되어 해당하는 에폭시알코올을 좋은 수득율로 얻을수 있음을 알 수 있었다. Reduction of epoxy ketones with zinc borohydride proceeds selectively to the corresponding epoxy alcohols in good yields. Thus we obtained 3,4-epoxy-4-methyl-2-pentanol($79.8{\%}$), trans-isophorol oxide ($89.5{\%}$), trans-2-benzal-cyclohexanol oxide ($84.1{\%}$) and trans-chalcol oxide ($97.9{\%}$, crude) from the corresponding epoxy ketones.