• Bulletin of the Korean Chemical Society
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• v.7 no.1
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• pp.70-73
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• 1986

New amino protective reagents, t-butyl benzotriazol-1-yl carbonate and benzyl benzotriazol-1-yl carbonate, for t-butoxycarbonylation and benzyloxycarbonylation of amines and amino acids have been developed. t-Butyl benzotriazol-1-yl carbonate reacts rapidly and cleanly with various amines and amino acids to afford N-Boc amines and N-Boc amino acids in high yields and benzyl benzotriazol-1-yl carbonate is also found to be very effective in the benzyloxycarbonylation of amino acids.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1C
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• pp.86-93
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• 2008

The Galileo system, a global navigation satellite system(GNSS) developed by E.U., uses the direct sequence/spread spectrum(DS/SS) modulation. A DS/SS-based system performs a fine synchronization between the received and locally generated spreading signals, via attacking process. In the absence of multipath signals, using the symmetric characteristic of the correlation function, the delay lock loop with the early minus late discriminator(EL-DLL) offers the best performance in tracking. However, in the presence of multipath signals, the symmetry of the correlation function could be lost, causing a tracking bias. In this paper, we observe that the correlation values in the advanced offset range remain almost unchanged, due to the multipath signals being received later than a line-of-sight signal. Based on this observation, we propose a novel tracking scheme for a Galileo BOC(1,1) system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.6
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• pp.350-356
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• 2014

In this paper, we design a local signal to improve a tracking performance of time-multiplexed binary offset carrier (TMBOC) signal, which was adopted in modernized global positioning systems (GPS). Specifically, considering that TMBOC signal includes BOC(6,1) components, we first obtain local signal by evenly dividing sub-carrier of TMBOC(6,1,4/33) by the period of a BOC(6,1) pulse. Finally, we remove side-peaks of TMBOC(6,1,4.33) autocorrelation via combination of partial correlations given from designed local signal and solve the ambiguity problem. From numerical results, when performing signal tracking using the designed local signal, we demonstrate that the improved tracking error standard deviation (TESD) performance is offered as compared its autocorrelation and the conventional correlation functions.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.125-129
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• 2006

Japan has been investigating a new satellite based positioning system called Quasi-Zenith Satellite System (QZSS). Since the improvement of positioning availability in urban area is one of the most important advantages of the QZSS, multipath mitigation is a key factor for the QZSS positioning system. Therefore, Japan Aerospace Exploration Agency (JAXA) and GNSS Inc. have commenced the R&D of a pseudolite, which transmits the next-generation signal such as BOC(1,1), in order to evaluate the effect of multipath on the new signal. A prototype BOC pseudolite was developed in 2005, and ground tests showed a capability of generating proper pseudorange. Also, preliminary flight experiments using a pseudo quasi-zenith satellite, a helicopter on which the pseudolite is installed, were conducted in early 2006, and the BOC-type correlation function was monitored in real time.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.05a
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• pp.145-145
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• 2003

A method for the determination of alkylphenols, chlorophenols and bisphenol A in paper materials using GC/MS-SIM has been developed. Eleven endocrine disrupting chemicals (EDCs) of phenols in paper samples were extracted with acetonitrile. Also, solid-phase extraction (SPE) with XAD-4 and subsequent conversion to isobutoxycarbonyl derivatives or tert.-butyldimethylsilyl derivatives for sensitive analysis with the selected ion-monitoring (SIM) mode. The recoveries were 82.4∼108.8 % by area ratio of pheranthrene-d$\sub$10/ vs bisphenol A d$\sub$l6/. (isoBOC derivatization and TBDMS derivatization) The SIM responses were linear with the correlation coefficient varying 0.9717∼0.9995 (isoBOC derivatization), and 0.9842∼0.9980 (TBDMS derivatization). The range of concentrations was respectively, 0.95∼l.44 ng/g in 2,4-dichlorophenol, 1.01∼1.17 ng/g in t-butylphenol, 2.17∼5.84 ng/g in pentachlorophenol, 12.68∼14.88 ng/g in nonylphenol and 30.84∼153.72 ng/g in bisphenol A.

• Bulletin of the Korean Chemical Society
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• v.12 no.1
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• pp.71-74
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• 1991

Facile methods are reported for the synthesis of optically pure derivatives of (2S,3R)-3-amino-2-hydroxy-4-(4'-hydroxyphenyl)b utanoic acid. To avoid troublesome synthesis of O-benzyl-N-Boc-D-tyrosine, without the protection of phenolic OH group of tyrosine N-Boc-D-tyrosine methyl ester was reduced with DiBAL to the aldehyde. The aldehyde was converted via the cyanohydrin to (2S,3R)-3-amino-2-hydroxy-4-(4'-hydroxyphenyl)butanoic acid (AHpHBA). The mixture of diastereomers was converted to the corresponding Boc-AHpHBA methyl ester derivatives and separated by chromatography over silica gel. Optically active (2S,3R)-AHpHBA was used to synthesize aminopeptidase inhibitors.

• The Journal of Natural Sciences
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• v.9 no.1
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• pp.95-104
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• 1997

We synthesized the following series of 3', 5'hydroxy modified thymidine analogs to check the potential asymmetric catalytic effects. 3'-monomethylammino and dimethylaminothymidine was synthesized from thymidine via 8 step and 7 step in 38%, 20% overall yields respectively. 5'Acetyl-3'-dimethylamino thymidine was prepared from thymidine via 8 step in 40% overall yield. 5‘-TBS-3'-up-t BOC methylamino thymidine was prepared from thymidine via 6 step in 30% overall yield. 3'-acetyl-5'-t BOC amino thymidine was prepared from thymidine via 7 step in 31% overall yield.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.220-220
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• 1994

출발물질로 L-tyrosine을 사용하여 요오드화, 에스테르화, N-BOC 및 0-Bn보호기화 및 N 탈보호기화를 행하여 5단계에 걸쳐 41%의 수율로 methyl 0-Bn-3-iodotyrosinate를 합성하였다. 또한 Ullmann coupling의 반응성 향상을 위해 5위치에 nilro기가 도입된 methyl 0-Bn-3-iodo-5-nitrotyrosinate를 좋은 수율로 합성하였다. 이들에 N-BOC-tyrosine을 결합시켜 대응하는 dipeptide를44% 및 39%의 수율로 각각 얻었다. 일단 dipeptide에 대해 Ullmann coupling을 행하였으나 원하는 cyclic product는 얻을수 없었다. 전년도에 이어 methyl N-BOC-0-Bn-3-hydroxytyrosinate를 합성하였다. 이로 부터 4-iodobenzaldehyde에 Ullmann coupling을 행하여 원하는 페놀성 biaryl ether를 합성하고자 하였다. 또한 $\beta$-hydroxyhomoserine의 합성을 위해 출발물질로 cis-1,4-buterdiol을 사용하여 12단계의 합성반응을 행하여 좋은수율로 원하는 화합물을 합성하였다.

• Macromolecular Research
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• v.11 no.1
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• pp.69-72
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• 2003

A homopolymer having pendent t-Boc-protected quinizarin moieties has been prepared for patterned fluorescence images. The homopolymer P(t-BQN (2-norbornenylmethyl di-tert-butoxycarbonylquinizarin)) 5 was prepared by palladium-catalyzed addition polymerization. The t-Boc-protecting groups of the polymer were efficiently removed during chemical amplification process and revealed original properties of quinizarin, allowing patterned fluorescence images in the polymer film.

• The Korean Journal of Nuclear Medicine
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• v.36 no.6
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• pp.333-343
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• 2002

Purpose: A new linker, hydrazino nicotinamide (HYNIC), was recently introduced for labelling of liposome with $^{99m}Tc$. In this study we synthesized HYNIC derivatized PEG (polyethylene glycol)-liposomes radiolabeled with $^{99m}Tc$. Materials and Methods: In order to synthesize HYNIC-DSPE (distearoyl phosphatidyl ethanolamine) which is a crucial component for $^{99m}Tc$ chelation, first of all succinimidyl 6-BOC-hydrazinopyridine-3-carboxylic acid was synthesized from 6-chloronicotinic acid by three sequential reactions. A DSPE derivative of succinimidyl 6-BOC-hydrazinopyridine-3-carboxylic acid was transformed into HYNIC-DSPE by HCI/dioxane. HYNIC-PEG-liposomes were prepared by hydration of the dried lipid mixture of EPC (egg phosphatidyl choline): PEG-DSPE : HYNIC-DSPE:cholesterol (1.85:0.15:0.07:1, molar ratio). The HYNIC-PEG-liposomes were labeled with $^{99m}Tc$ in the presence of $SnCl_2{\cdot}2H_2O$ (a reducing agent) and tricine (a coligand). To investigate the level of in vivo transchelation of $^{99m}Tc$ in the liposomes, the $^{99m}Tc$-HYNiC-PES-liposomes were incubated with a molar excess of DTPA, cysteine or glutathione solutions at $37^{\circ}C$ for 1 hour. The radiolabeled liposomes were also incubated in the presence of human serum at $37^{\circ}C$ for 24 hours. Results: 6-BOC-hydrazinopyridine-3-carboxylic acid was synthesized with 77.3% overall yield. The HYNIC concentration in the PEG-coated liposome dispersion was 1.08 mM. In condition of considering the measured liposomal size of 106 nm, the phospholipid concentration of $77.5\;{\mu}mol/m{\ell}$ and the liposomal particle number of $5.2{\times}10^{14}$ liposomes/ml, it is corresponded to approximate 1,250 nicotinyl hydrazine group per liposome in HYNIC-PEG-liposome. The removal of free $^{99m}Tc$ was not necessary because the labeling efficiency were above 99%. The radiolabeled liposomes maintained 98%, 96% and 99%, respectively, of radioactivity after incubation with transchelators. The radiolabeled liposomes possessed above 90% of the radioactivity in serum. Conclusion: These results suggest that the HYNIC can be synthesized easily and applied in labelling of PEG-liposomes with $^{99m}Tc$.