Browsing by Author "Chiu, Cheng-Hsin"

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(2-Ketulosonyl)onate 2,3-O-thionocarbonate donors for the synthesis of KO and KDO alpha-glycosides and a one-pot glycosylation method for 2-keto acid donors
(2020-08-21)
Mong, Kwok-Kong Tony
;
Pradhan, Tapan Kumar
;
Chiu, Cheng-Hsin
;
Hung, Wei-Cheng
;
Chen, Chao-Ju
We report a short synthetic strategy for direct preparation of (2-ketulosonyl)onate donors. These donors feature a cyclic thionocarbonate group at the C2 and C3 positions, which plays a multitude of chemical roles. It protects the C2 and C3 hydroxyls during building block preparation. In glycosylation, the thionocarbonate can be activated by a sulfenylating promoter and serves as a leaving group. Because of its beta-configuration, it also plays the role of a stereo-directing group during the formation of the alpha-glycosidic bond. In addition, the thionocarbonate donors can couple with thioglycoside acceptors. This orthogonal property was used for the development of the first one-pot glycosylation method for 2-keto acid sugars.
Convergent Synthesis of Macrocyclic and Linear Desferrioxamines
(1970-01-01)
Chiu, Cheng-Hsin
;
Jheng, Ting-Cian
;
Peng, Bo-Chun
;
Chung, Wen-Sheng
;
Mong, Kwok-kong Tony
Polyhydroxamate desferrioxamines (DFO) are nontoxic siderophores endowed with high potential for development of therapeutic chelating agents. Herein, we report a modular and convergent strategy for diverse synthesis of macrocyclic and linear DFOs. The strategy employed orthogonally protected N-hydroxy-N-succinylcadaverine building blocks, which allowed bidirectional extension of the DFO structure. The efficiency of the new strategy was demonstrated by the total synthesis of 44-membered macrocyclic DFO-T-1, as well as four related DFO compounds in 11-13 linear steps and 2.1 %-10 % overall yields. Comparison of the iron binding affinity of the DFOs revealed DFO-E as the best chelator.