Chultack Lim
Kyushu University
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Featured researches published by Chultack Lim.
Tetrahedron Letters | 1997
Chultack Lim; Sung-Hong Kim; Soo-Dong Yoh; Mizue Fujio; Yuho Tsuno
Abstract 1-Arylethyl bromides react with pyridine in acetonitrile by unimolecular and bimolecular processes. These processes are quite distinct and this fact affords clear evidence for the duality of clean S N 1 and S N 2 mechanisms, occurrence of independent S N 1 and S N 2 reaction processes without an intermediate mechanism.
Tetrahedron Letters | 2000
Kumi Matohara; Chultack Lim; Mikio Yasutake; Rika Nogita; Toru Koga; Youichi Sakamoto; Teruo Shinmyozu
The photolysis of [3 3 ](1,3,5)cyclophane 8 in MeOH:2N HCl (17:1 v/v) afforded new polycyclic caged dimethoxy and methoxy–hydroxy compounds 12 and 13 with a novel pentacyclo[6.4.0.0 3,7 .0 4,11 .0 5,10 ]dodecane skeleton 7 , in addition to methyl ether 9c with the previously reported skeleton 6 . The unique structural features of 12 and 13 were elucidated by X-ray structural analysis.
Tetrahedron Letters | 1999
Youichi Sakamoto; Tsutomu Kumagai; Kumi Matohara; Chultack Lim; Teruo Shinmyozu
Abstract Photoirradiation of [3 3 ](1,3,5)cyclophane 11 with a low pressure Hg lamp in CH 2 Cl 2 in the presence or absence of water afforded new polycyclic cage compounds of chlorinated tribridged hexacyclododecane 12 or its hydroxy analogue 14 and tribridged tetracyclic olefin 13 .
Angewandte Chemie | 2000
Chultack Lim; Mikio Yasutake; Teruo Shinmyozu
Abnormally long C-C single bonds are found in the polycyclic caged diol with a pentacyclo[6.3.0.1(4,11).0(2,6).0(5,10)]dodecane skeleton formed by photolysis (see scheme). This skeleton resembles the structure of diamantane, but instead of having six cyclohexane rings in a chair conformation it contains only two cyclohexane rings in a distorted chair conformation and four cyclopentane rings, which makes it more highly strained than diamantane.
Tetrahedron Letters | 1999
Chultack Lim; Mikio Yasutake; Teruo Shinmyozu
Abstract The photolysis of [34](1,2,3,5)cyclophane 5 in H2O-saturated CH2Cl2 produced the novel polycyclic caged diol 6 with a pentacyclo[6.3.1.16,10.03,7.04,10]dodecane skeleton 4, which has abnormally elongated CC single bonds (1.624 A). The structural features of 6 were studied using the X-ray structural analysis and ab initio MO calculations.
European Journal of Organic Chemistry | 1999
Wakana Sentou; Teizi Satou; Mikio Yasutake; Chultack Lim; Youichi Sakamoto; Tetsuji Itoh; Teruo Shinmyozu
The modified synthetic route to [34](1,2,4,5)cyclophane (3) provides gram quantities of this compound in fewer steps than the conventional routes. The cycloaddition of 3 with dicyanoacetylene (12) gave barrelenophane 13, which was transformed into semibullvalenophane 15 on photoirradiation. This transformation (13 15) is in sharp contrast to the case of Boekelheides [24]barrelenophane, where cyclooctatetraenophane is obtained. The X-ray structural analyses of 3, 13, and 15 demonstrates their unique structures.
Journal of Physical Organic Chemistry | 1998
Sung Hong Kim; Soo-Dong Yoh; Chultack Lim; Masaaki Mishima; Mizue Fujio; Yuho Tsuno
The rate data for the Menschutkin reaction between strongly activated Z-substituted benzyl p-toluenesulfonates and Y-substituted N,N-dimethylanilines in acetonitrile at 35 °C fit the equation, kobs = k1 + k2 [DMA], which is consistent with concurrent first- and second-order processes. The k1 and k2 values for each substrate were separated based on the above equation. The SN1 rate constant, k1, is unaffected by the nature of the nucleophile, whereas the SN2 rate constant, k2, increased with the electron-donating substituent of the N,N-dimethylaniline. The substituent effect on the k1 values is linearly correlated by the Yukawa–Tsuno equation with ρ = −5.2 and r = 1.3. The unimolecular reaction can be regarded as a classical SN1 mechanism. In contrast, that on the k2 values shows an upward curvature when analyzed by the Brown σ+ treatment. These results are ascribed to the simultaneous and independent occurrence of SN1 and SN2 mechanisms in the present Menschutkin reaction.
Angewandte Chemie | 2000
Chultack Lim; Mikio Yasutake; Teruo Shinmyozu
Ungewohnlich lange C-C-Einfachbindungen liegen in dem photochemisch erhaltenen polycyclischen Kafigdiol vor, das ein Pentacyclo[6.3.0.14,11.02,6.05,10]dodecan-Skelett enthalt (siehe Schema). Dieses Gerust ahnelt dem von Diamantan, enthalt aber im Unterschied zu diesem nicht sechs Cyclohexanringe in Sesselkonformation, sondern zwei Cyclohexanringe in einer verzerrten Sesselkonformation und vier Cyclopentanringe, weshalb es wesentlich starker gespannt ist als Diamantan.
Journal of the American Chemical Society | 2004
Rika Nogita; Kumi Matohara; Minoru Yamaji; Takuma Oda; Youichi Sakamoto; Tsutomu Kumagai; Chultack Lim; Mikio Yasutake; Tetsuro Shimo; Charles W. Jefford; Teruo Shinmyozu
ChemInform | 2004
Teruo Shinmyozu; Rika Nogita; Motoko Akita; Chultack Lim