• Bulletin of the Korean Chemical Society
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• 제29권4호
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• pp.827-832
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• 2008

A new diarylethene compound with donor and acceptor substituent was synthesized from 2,3-bis(2-methylbenzo[b]thiophene-3-yl)hexafluorocyclopentene (BTF) over 5 steps. The donor-acceptor structured BTF compound (TBTFE) showed spectral change to a longer wavelength through photochromism with a high cyclization quantum yield (0.56). The 3,4-ethylenedioxythiophene (T) and carboethoxy (E) groups directly connected to BTF unit promoted electrical change accompanied with the photoisomerization of the BTF unit. Photo-induced electrical switching was achieved from a photocell containing TBTFE doped polymer film, which showed reversible and stable current change over repeated cycles by the alternative UV/Vis irradiation, as estimated by the I-V plot.

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1531-1534
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• 2009

(2S,3R)-3-Hydroxy-2-(hydroxymethyl)-3,6-dihydro-2H-pyridine 8, an important precursor for the synthesis of polyhydroxylated piperidine azasugars, has been prepared from L-serine. Highly stereoselective nucleophilic addition to amino aldehyde 5 gave the corresponding allylic alcohol 6 which proceeded to give dihydro-2H-piridine 7a via a Grubbs II catalyzed RCM. Stereoselective H-bond directed epoxidation of allylic alcohol led to the oxiranyl alcohol 9 which was easily converted to L-deoxyaltronojirimycin by regioselective ring opening.

• Archives of Pharmacal Research
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• 제17권3호
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• pp.204-206
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• 1994

A regioselective perparation of 10-methoxy-11-hydroxyaporphine ("Apocodeine, 1b") form (R, S)-10, 11-dihydroxyaporphine(apomorphine, 1a) is described. The isopropylidene ketal ring of 10, 11-(isopropylidenyldioxy) aporphine (2) obtained by the isopropylidenation of apomorphine, was regioselectively opened by the ten equivalent of timethylaluminum to give 100-hydroxy-11-t-butyloxyaporphine (3). The free 10-hydroxyl position of 3 was methylated with methyl p-toluenesulfonate/NaH, and afforded 10-methoxy-11-t-butyloxyaporphine (4) in high yield. Selective debutylation gave the desired 10-methoxy-11-hydroxyaporphine("apocodeine", 1b) in good yield.

• Bulletin of the Korean Chemical Society
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• 제7권5호
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• pp.372-376
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• 1986

Substituted 3,4-dihydro-2H-pyrans ($1_{a-e}$) were prepared by (4 + 2) cycloaddition reaction of dimethyl dicyanofumarate with the corresponding electron-rich olefins. The compounds $1_{a-e}$ were ring-open polymerized by cationic initiators to obtain polymers of 1:1 alternating sequence. Polymerizations were carried out with boron trifluoride etherate in methylene chloride at $-78^{\circ}C$. All the polymers obtained were soluble in common solvents and were reprecipitated by pouring its chloroform solution into diethyl ether. All the compounds $1_{a-e}$ were not as reactive as the corresponding pyrans derived from ${\alpha}$ -cyanoacrylate.

• Bulletin of the Korean Chemical Society
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• 제9권3호
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• pp.176-179
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• 1988

3-Methoxy-4-cyano-2,9-dioxabicyclo[4.3.0]non-3-e ne (1) was prepared by (4 + 2) cycloaddition reaction of methyl ${\alpha}$-cyanoacrylate with 2,3-dihydrofuran. Compound 1 was ring-open polymerized by cationic catalyst such as boron trifluoride etherate to obtain alternating head-to-head (H-H) copolymer (2) of methyl $\alpha$ -cyanoacrylate and 2,3-dihydrofuran. For comparison, head-to-tail (H-T) copolymer (3) was also prepared by free radical copolymerization of the corresponding monomers. The H-H copolymer exhibited minor differences in its $^1H$-NMR and IR spectra, but in the $^{13}C$-NMR spectra significant differences were observed between the H-H and H-T copolymers. All of the H-H and H-T copolymers were soluble in common solvents and the inherent viscosities were in the range 0.2-0.3 dl/g.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1988년도 가을 학술발표회 논문집
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• pp.24-29
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• 1988

In this paper, it is proposed hew the rigid element method suggested in the first paper can be applied to the elastic and elasto-plastic analysis of spherical shell with the open stiff ring. In the analytical model, the solution domain is divided into rectangular-shaped spherical bending elements. Each contact surface of two adjacent elements is interconnected with four elastic springs, and it is assumed that the internal forces are distritributed into springs. The 6 degrees of freedom of the element are placed in the center of elements, and the 6 cen-teroidal rigid displacements affect other elements through springs around elements. And then the solution domain is estimated by the behavior of elements and springs. In this study, these concepts are applied to the elastic and elasto-plastic analysis for the eight cases of the spherical shell according to the condition of stiff ring, the condion of loading and the size of opening. And then some numerical results such as the distribution of stresses, the force-displacement curves and the mode of fractures will he shown.

• 한국전자파학회논문지
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• 제18권3호
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• pp.315-322
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• 2007

본 논문에서는 UHF RFID Reader 장치에서 고주파 신호 송신을 위한 발진기형 능동 안테나를 설계 제작하였다. 능동 안테나의 방사체로는 임피던스 정합이 용이하면서 좌선 원형 편파 특성을 갖는 소형화된 사각형 링 패치 안테나가 제안되었다. 이를 기반으로 링 패치 내부의 빈 공간에 RF증폭 회로를 위치시켜 사각형 링 패치와 상호연결하여 궤환 구조를 형성함으로써 발진 회로를 구성하였다. 발진 중심 주파수는 915 MHz이며 링 패치는 발진기의 공진기로 활용하였다. 실험 결과, 임피던스 대역폭 29 MHz, 3 dB 축비 대역폭 20 MHz, 3 dB 빔폭 $85^{\circ}$, 그리고 유효 방사 전력을 8.8 dBm을 얻었다.

• Bulletin of the Korean Chemical Society
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• 제26권5호
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• pp.829-832
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• 2005

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2007년도 학술발표회 논문집
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• pp.97-100
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• 2007

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• Bulletin of the Korean Chemical Society
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• 제23권11호
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• pp.1611-1615
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• 2002

The ring opening of epoxides with elemental iodine and bromine in the presence of three diamine podands 7-9 as new catalysts affords vicinal iodo alcohols and bromo alcohols in high yields. This new procedure occurs regioselectively under neutral and mild conditions in various aprotic solvents even when sensitive functional groups are presented.