1235555-31-3Relevant articles and documents
Donor-Reactivity-Controlled Sialylation Reactions
Asressu, Kesatebrhan Haile,Chang, Chun-Wei,Lam, Sarah,Wang, Cheng-Chung
, p. 4525 - 4530 (2021/08/09)
Although tremendous efforts have been made for the efficient preparation of sialosides, controlling the stereochemical outcome of sialylation reaction still remains one of the most challenging tasks due to the unique chemical structure of sialic acid. We developed a new strategy to statistically analyze the stereoselectivity of sialylation reactions on six types of p-tolyl thiosialosides in NIS/TfOH system using Relative Reactivity Value (RRV) as the indicator. Analysis of the reaction mechanism showed the formation of the relatively stable glycosyl bromide and glycosyl chloride intermediates from halide- and triflate-containing promotors in the absence of an acceptor. We found that the α/β-stereoselectivity, yields, and intermediate changes were associated with their donor reactivity. These findings enable to tailor the most suitable building blocks for stereo-controlled sialylation reactions.
5- N,4- O -carbonyl-7,8,9-tri- O -chloroacetyl-protected sialyl donor for the stereoselective synthesis of α-(2→9)-tetrasialic acid
Lin, Chang-Ching,Lin, Nai-Pin,Sahabuddin, L. Sk,Reddy, Vijaya Raghava,Huang, Li-De,Hwang, Kuo Chu,Lin, Chun-Cheng
experimental part, p. 4921 - 4928 (2010/10/21)
(Figure presented) An efficient stereoselective synthesis of α-(2→9)-tetrasialic acid was achieved using tri-O-chloroacetyl- derivatized sialyl donor and a triol sialyl acceptor. Both the acceptor and the donor were also protected with a cyclic 5-N-4-O-carbonyl protecting group. The donor is highly reactive and enabled α-selective sialylation with various primary, secondary, and tertiary acceptors under in situ activation conditions (NIS/TfOH, -78 °C, acetonitrile/dichloromethane). The trans-fused oxazolidinone ring and O-chloroacetyl protecting groups were easily removed under mild reaction conditions to provide the fully deprotected α(2→9)-tetrasialic acid.