• Bulletin of the Korean Chemical Society
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• 제26권1호
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• pp.43-46
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• 2005

Reaction energies were determined for reductive ring-opening reactions of Li$^+$-coordinated ethylene carbonate (EC) and vinylene carbonate (VC) by a density functional method. We have also explored the ring-opening of Li$^+$-EC and Li$^+$-VC by reaction with a nucleophile (CH$_3$O$^-$.) thermodynamically. Our thermodynamic calculations led us to conclude that the possible reaction products are CH$_3$OCH$_2$CH$_2$OCO$_2$Li (O$_2$-C$_3$ cleavage) for Li$^+$-EC +CH$_3$O$^-$., and CH$_3$OCHCHOCO$_2$Li (O$_2$-C$_3$ cleavage) and CH$_3$OCO$_2$CHCHOLi (C$_1$-O$_2$ cleavage) for Li$^+$-VC +CH$_3$O$^-$.. The opening of VC would occur at the C$_1$-O$_2$ side by a kinetic reason, although the opening at the O$_2$-C$_3$ side is more favorable thermodynamically.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2286-2290
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• 2013

Ring opening reactions of epoxides with oxygen nucleophiles catalyzed by a variety of quaternary onium salt, such as ammonium or phosphonium salt were explored. The results showed that tetrabutylphosphonium bromide (TBPB) among salts serves as the most efficient catalyst for this process and that expoxide ring opening reactions with a variety of oxygen nucleophiles including carboxyic acid and phenol, promoted using this salt, lead to generate readily purifiable products in excellent yields.

• Bulletin of the Korean Chemical Society
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• 제20권6호
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• pp.663-666
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• 1999

The 4-methylene-1,3-dioxolane(4-MDO) derivatives with dimethoxyphenyl group on the 2-position of 1,3-dioxolane ring, 2-(x,y-dimethoxyphenyl)-4-MDO derivatives (x,y=2,3(1b), 2,4(2b), 2,5(3b) and 3,4(4b)) were prepared by acelalizationof the corresponding benzaldehyde with 3-chloro-1,2-propanediol, followed by dehydrochlorination. 2-(Dimethoxy)phenyl-4-MDO derivatives underwent polymerization wiht ring opening as will as cyclization reaction to afford a mixture of the ring-opened polymer and 3(2H)-dihydrofuranone derivative with boron trifluoride as a cationic catalyst. Both the methylene group and 1,3-dioxolane ring were participated in the reaction with cationic catalyst. The key intermediate of the polymerization is a benzyl cation generated by ring opening, and the cyclization reaction proceed via proton addition to oxygen atom of 1,3-dioxolane ring.

• Bulletin of the Korean Chemical Society
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• 제7권3호
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• pp.210-213
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• 1986

1,1-Dicyano-2-ethoxycyclobutane (1a) was prepared by [2 + 2] cycloaddition reaction of vinylidene cyanide with ethyl vinyl ether. 1,1-Dicyano-2-phenylcyclobutane (1b) was prepared by the reactions involving the reduction of cinnamyl alcohol, chlorination, cyanomethylation, bromination, and ring-closure reaction. Compound 1a was ring-opening polymerized with NaCN or n-butyllithium to give a low molecular weight polymer. The compound 1b however, failed to polymerize by either anionic or radical catalysts.

• Bulletin of the Korean Chemical Society
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• 제26권9호
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• pp.1339-1343
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• 2005

The N-inversion energies and nucleophilic ring-opening reactions of N-substituted aziridine compounds are investigated using B3LYP/6-31+$G^*$ methods, where substituents (R) on the nitrogen atom has been H (1), Me (2), Ph (3), Bn (4), CHMePh (5), $CO_2Me$ (6), COPh (7) and $SO_2Ph$ (8). The N-inversion energy with X group are decreased as the following order: R = CHMePh (17.06 kcal/mol) $\gt$ Me (16.97) $\gt$ Bn (16.70) $\gt$ H (16.64) $\gt$ $SO_2Ph$ (12.18) $\gt$ Ph (8.91) $\gt$ COPh (5.75) $\gt$ $CO_2Me$ (5.48). For reactivity of the ring opening toward cyanide ion, the aziridine 6 (R=$CO_2Me$) is shown to be the most reactive one. During the ring opening of aziridine 6 by CN$^{\ominus}$, the torsional OCNC angle becomes near to $180^{\circ}$, where the geometry allows for the effective incorporation of electrons of the nitrogen atom to the C=O bond. It would be a possible driving force for nucleophilic ring opening reaction as well as decreasing the N-inversion energy barrier. Regarding to the regioselectivity, the orientation of nucleophile in ring opening reaction appears to be different in the case of 9 and 10. The results are discussed in terms of steric/electronic effect of the $C_2$-substituents.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1741-1744
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• 2013

A new polymeric catalyst was prepared by supporting $GaCl_3$ on cross-linked polyvinylpyrrolidone ($GaCl_3$/PVP). This catalyst was employed for efficient and regioselective ring-opening reaction of epoxides by various alcohols under solvent-free conditions at room temperature. In our procedure, this heterogeneous catalyst was used at neutral and mild reaction conditions to afford high yields of ${\beta}$-alkoxy alcohols. Also, regioselective conversion of epoxides to ${\beta}$-azidohydrines was accomplished by sodium azide in MeOH in the presence of $GaCl_3$/PVP at room temperature. $GaCl_3$/PVP is a non-hygroscopic and recoverable catalyst and is easily separated from reaction mixture by a simple filtration and re-used repeatedly. Also, this catalyst has good handling and can be stored for long time without any reducing of its reactivity.

• 통합자연과학논문집
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• 제5권2호
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• pp.91-99
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• 2012

A newly-devised Meerwein-Ponndorf-Verley (MPV) reagents, such as diisobutylacetoxyalanes and diisobutylmethanesulfonylalanes, achieved a clean conversion of unsymmetrical epoxides to the corresponding less substituted alcohols. This review covers the recent developments for such a regiospecific ring-opening reaction of epoxides.

• 대한화학회지
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• 제13권3호
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• pp.229-232
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• 1969

2,2-gem-dephenylaziridine의 醋酸에 의한 開環反應에서 反應生成物은1,1-diphenyl-2-amino-ethyl acetate 임을 알았다. 또한 이 開環反應은 aziridine環 안에 있는 窒素原子와 tertiary炭素原子사이의 結合이 切斷되어 中間體로서 carbonium이온이 形成되는 過程을 거쳐서 進行됨을 알았다.

• Bulletin of the Korean Chemical Society
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• 제10권4호
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• pp.404-406
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• 1989

• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1283-1284
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• 2006