Browsing by Author "Chang, Shih-Sheng"

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A mild and general method for preparation of alpha-glycosyl chlorides
(2009-08-05)
Chang, Chih-Wei
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Chang, Shih-Sheng
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Chao, Chin-Sheng
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Mong, Kwok-Kong T.
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應用化學系
A mild and efficient chlorination method for production of glycosyl chlorides is first described which employs inexpensive trichlorotriazine (TCT) and DMF as a chlorination reagent and is compatible with typical acid-labile hydroxyl protecting functions. The scope and limitations, reaction mechanism and its application in the sequential glycosylations are discussed. (C) 2009 Elsevier Ltd. All rights reserved.
A straightforward alpha-selective aromatic glycosylation and its application for stereospecific synthesis of 4-methylumbelliferyl alpha-T-antigen
(2009-03-10)
Chang, Shih-Sheng
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Lin, Chun-Cheng
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Li, Yaw-Kuen
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Mong, Kwok-Kong Tony
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應用化學系
A practical and efficient alpha-selective aromatic glycosylation with simple per-O-acetyl glycopyranosyl trichloroacetimidates is reported. The method is particularly effective for L-fucosyl and 2-azido-2-deoxy-D-galatosaminyl imidates, with which exclusive alpha-selectivity was achieved. The synthetic utility of this method was demonstrated in the stereoselective synthesis of 4-methylumbelliferyl alpha-T-antigen. (C) 2008 Elsevier Ltd. All rights reserved.
An Intelligent Telecardiology System Using a Wearable and Wireless ECG to Detect Atrial Fibrillation
(2010-05-01)
Lin, Chin-Teng
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Chang, Kuan-Cheng
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Lin, Chun-Ling
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Chiang, Chia-Cheng
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Lu, Shao-Wei
This study presents a novel wireless, ambulatory, real-time, and autoalarm intelligent telecardiology system to improve healthcare for cardiovascular disease, which is one of the most prevalent and costly health problems in the world. This system consists of a lightweight and power-saving wireless ECG device equipped with a built-in automatic warning expert system. This device is connected to a mobile and ubiquitous real-time display platform. The acquired ECG signals are instantaneously transmitted to mobile devices, such as netbooks or mobile phones through Bluetooth, and then, processed by the expert system. An alert signal is sent to the remote database server, which can be accessed by an Internet browser, once an abnormal ECG is detected. The current version of the expert system can identify five types of abnormal cardiac rhythms in real-time, including sinus tachycardia, sinus bradycardia, wide QRS complex, atrial fibrillation (AF), and cardiac asystole, which is very important for both the subjects who are being monitored and the healthcare personnel tracking cardiac-rhythm disorders. The proposed system also activates an emergency medical alarm system when problems occur. Clinical testing reveals that the proposed system is approximately 94% accurate, with high sensitivity, specificity, and positive prediction rates for ten normal subjects and 20 AF patients. We believe that in the future a business-card-like ECG device, accompanied with a mobile phone, can make universal cardiac protection service possible.
Low-Concentration 1,2-trans beta-Selective Glycosylation Strategy and Its Applications in Oligosaccharide Synthesis
(2009)
Chao, Chin-Sheng
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Li, Chen-Wei
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Chen, Min-Chun
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Chang, Shih-Sheng
;
Mong, Kwok-Kong Tony
This study develops an operationally easy, efficient, and general 1,2-trans beta-selective glycosylation reaction that proceeds in the absence of a C2 acyl function. This process employs chemically stable thioglycosyl donors and low substrate concentrations to achieve excellent beta-selectivities in glycosylation reactions. This method is widely applicable to a range of glycosylsubstrates irrespective of their structures and hydroxyl-protecting functions. This low-concentration 1,2-trans beta-selective glycosylation in carbohydrate chemistry removes the restriction of using highly reactive thioglycosides to construct 1,2-trans beta-glycosidic bonds. This is beneficial to the design of new strategies for oligosaccharide synthesis, as illustrated in the preparation of the biologically relevant beta-(1 -> 6)-glucan trisaccharide, beta-linked Gb(3) and isoGb(3) derivatives.
Rate-Dependent Inverse-Addition beta-Selective Mannosylation and Contiguous Sequential Glycosylation Involving beta-Mannosidic Bond Formation
(2010)
Chang, Shih-Sheng
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Shih, Che-Hao
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Lai, Kwun-Cheng
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Mong, Kwok-Kong Tony
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應用化學系
"The beta-selectivity of mannosylation has been found to be dependent on the addition rate of the mannosyl trichloroacetimidate donor in an inverse-addition (I-A) procedure. This rate dependent I-A procedure can improve the selectivity of direct beta-mannosylation and is applicable to orthogonal glycosylations of thioglycoside acceptors. Further elaboration of this novel procedure enables the development of the contiguous sequential glycosylation strategy, which streamlines the preparation of oligosaccharides invoking beta-mannosidic bond formation. The synthetic utility of the contiguous glycosylation strategy was demonstrated by the preparation of the trisaccharide core of human N-linked glycoproteins and the trisaccharide repeating unit of the O-specific polysaccharide found in the cellular capsule of Salmonelle bacteria."