• Bulletin of the Korean Chemical Society
• /
• 제15권10호
• /
• pp.845-849
• /
• 1994

Tetracarbonylhydridoferrate, $HFe(CO)^-_4$, generated by the reaction of $Fe(CO)_5$ with alkaline solution, is a good reducing agent for mono-dehalogenation of gem-dihalocyclopropanes. It also acts as a good reducing catalyst under phase transfer reaction conditions. 1,1-Dibromo-2-phenylcyclopropane and 1,1-dichloro-2-phenylcyclopropane were reduced to the corresponding mono-dehalogenated products in excellent yields. Thermodynamically stable trans-l-bromo-2-phenyl cyclopropane was formed as the major product over the cis-isomer, trans/cis=3/2. The 1-bromo-2-phenyl cyclopropane radical intermediate was formed by single electron transfer from $HFe(CO)^-_4$. Dissociation of bromide anion, followed abstraction of hydrogen radical from alcoholic solvent would lead to the formation of the stable trans-isomer. The further mechanistic aspects were discussed.

• Bulletin of the Korean Chemical Society
• /
• 제21권6호
• /
• pp.595-603
• /
• 2000

Ring expansion reactions via endocyclic cleavage of cyclopropylcarbinyl radicals derived from the reaction of [1-benzyloxycarbonylbicyclo[n. 1.O]alk-(n+l)-yl] -1-imidazolethiocarboxylates with tributyltin hydride/AIBN proceeded to produce 3-cycloalkenecarboxylates in good yields. Benzyl (5'-phenoxypentyl) -3-cyclohepten-1 -carboxylate was obtained in 33% yield from the reaction of benzyl 5-methylenebicyclo [4. 1.0]- 1-carboxylates with 4-phenoxybutyl iodide under radical conditions. Selective cleavage of endocyclic bond in cyclopropane to the cyclohexane, results from stabilization of the resultant radical by the carbonyl groups, such as the benzyloxycarbonyl group, which lower the transition state energy for the final cyclopropane cleavage in the ring expansion.

• 대한화학회지
• /
• 제60권5호
• /
• pp.374-377
• /
• 2016

• Bulletin of the Korean Chemical Society
• /
• 제35권6호
• /
• pp.1706-1712
• /
• 2014

The OH($X^2{\Pi}$, ${\upsilon}^{\prime\prime}=0,1$) internal state distribution following the reaction of electronically excited oxygen atom ($O(^1D_2)$) with cyclo-$C_3H_6$ has been measured using laser-induced fluorescence, and compared with that following the reaction of $O(^1D_2)$ with $C_3H_8$. The overall characteristics of the OH internal energy distributions for both reactions were qualitatively similar. The population propensity of the ${\Pi}(A^{\prime})$ ${\Lambda}$-doublet sub-level suggested that both reactions proceeded via an insertion/elimination mechanism. Bimodal rotational population distributions supported the existence of two parallel mechanisms for OH production, i.e., statistical insertion and nonstatistical insertion. However, detailed analysis revealed that, despite the higher exoergicity of the reaction, the rotational distribution of the OH following the reaction of $O(^1D_2)$ with $C_3H_8$ was significantly cooler than that with cyclo-$C_3H_6$, especially in the vibrational ground state. This observation was interpreted as the effect of the flexibility of the insertion complex and faster intramolecular vibrational relaxation (IVR).

• Journal of Microbiology and Biotechnology
• /
• 제11권3호
• /
• pp.443-451
• /
• 2001

In order to investigate what kind of response anaerobic bifidobacteria has on oxygen stress, five oxygen-tolerant bifidobacteria were isolated from human fecal samples. All were temporarily identified as Bifidobacterium longum through an analysis of carbohydrate utilization patterns and cellular fatty acid profiles. In the presence of oxygen, the lag phase became extended and the cell growth was suppressed. Bifidobacterial cell was able to remove dissolved oxygen in an early stage of growth and to overcome oxygen stress to a certain extent. The cell became long n size and showed a rough surface containing many nodes which were derived from abnormal or incomplete cell division. Cellular fatty acid profiled changed remarkably under a partially aerobic condition, so that the carbon chain of cellular fatty acid became short. All the dimethyl acetals originated from plasmalogen were reduced, any cyclopropane fatty acid, 9, 10-methyleneoctadecanoic acid ($C_{19:0}cyc9,10$), was increased remarkably. Oxygen stress induced a 5.5 kD protein in B. longum JI 1 of the oxygen-teolerant bifidobacteria, that was named Osp protein, and its N-terminal amino acid sequence was as follows: unknown amino acid-Thr-Gly-Val-Arg-Phe-Ser-Asp-Asp-Glu. Therefore, the oxygen-tolerant bifidobacteria seemed to defend against oxygen stress byincreasing the content of short fatty acid and cyclopropane fatty acid, and induction of an oxygen stress protein, but not the plasmalogen.

• Bulletin of the Korean Chemical Society
• /
• 제34권3호
• /
• pp.868-874
• /
• 2013

Efficient synthetic route to novel 2'-spirocyclopropanoid 4'-deoxythreosyl phosphonic acid nucleosides was described from 1,4-dihydroxy-2-butene. Cyclopropane moiety was prepared via ester enolate alkylation using (2-chloroethyl)dimethylsulfonium iodide. Synthesized nucleoside analogues 16, 19, 23 and 26 were tested for anti-HIV activity as well as cytotoxicity. However, none of them showed any anti-HIV activity or cytotoxicity up to 100 ${\mu}M$.

• 대한화학회지
• /
• 제49권6호
• /
• pp.613-616
• /
• 2005

• 대한약학회:학술대회논문집
• /
• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
• /
• pp.366.2-366.2
• /
• 2002

In an effort to search for the chemically and enzymatically stable carbonucleoside. we designed ［1'-fluoro-2', 2'-bis-(hydroxymethyl) cyclopropyl methyl］ purines. The underlying concept for our design is to seek relatively conformationally-locked compound with minimal structural disturbance from acyclic carbonucleoside such as acyclovir or penciclovir. To meet such a requirement. we need to introduce cyclopropane and fluorine moiety. (omitted)

• 대한화학회지
• /
• 제29권3호
• /
• pp.213-219
• /
• 1985

고정된 사이크로 프로판환을 가진 양이온계에서 구조적 변화에 따른 상대적 안정도를 불소 19-핵자기공명분광기로 분석 검토했다. 이를 위해 8-파라-불화벤젠트리사이크로 옥탄 양이온과 9-파라불화벤젠 트리사이크로 노난 및 10-파라불화벤젠 트리사이크로데칸 양이온을 해당알코올과 불화황산과의 반응에서 얻었다. 풀루오르 19-NMR 스펙트럼에서 얻어진 결론은 사이크로프로판환이 양이온 탄소의 궤도와 ${\sigma}$ 컨쥬게이션을 위해 대칭적이며 바이섹트 구조의 유지가 하전의 안정화에 매우 중요한 요인인 반면, 사이크로 프로판기의 면과 양하전을 띈 탄소와 연결되는 결합각도(${\theta}$)의 변화는 하전의 안정화에 영향이 없음을 보여주었다.

• 접착 및 계면
• /
• 제13권4호
• /
• pp.163-170
• /
• 2012

${\beta}$-cyclodextrin은 다른 분자를 포접하여 inclusion complex (포접착물)를 만드는 특성을 가지고 있기 때문에 의약품, 농약, 식품, 화장품, 산화방지제, 휘발방지제, 흡습방지제, 퇴색방지제, 유화제 등의 다양한 용도로 사용되고 있다. 이러한 장점에도 불구하고 ${\beta}$-cyclodextrin은 물이나 유기용매에 대한 용해도가 낮아 사용에 제약을 받아왔다. 본 연구에서는 이러한 문제를 해결하기 위해서 Bisphenol-A나 폴리우레탄(PU) 발포제인 cyclopropane에 대한 포접특성을 갖고 물이나 유기용매에 대한 용해도가 향상된 polyol type의 ${\beta}$-cyclodextrin 유도체를 합성한 후 그 특성을 고찰하였다. 연구결과 합성된 polyol을 사용해서 제조한 경질 PU foam은 기존의 polyol과 비교해서 더 우수한 열전도 특성과 압축강도를 나타내었다.