352437-53-7Relevant academic research and scientific papers
1-Picolinyl-5-azido Thiosialosides: Versatile Donors for the Stereoselective Construction of Sialyl Linkages
Chen, Jian,Hansen, Thomas,Zhang, Qing-Ju,Liu, De-Yong,Sun, Yao,Yan, Hao,Codée, Jeroen D. C.,Schmidt, Richard R.,Sun, Jian-Song
, p. 17000 - 17008 (2019/11/16)
With the picolinyl (Pic) group as a C-1 located directing group and N3 as versatile precursor for C5-NH2, a novel 1-Pic-5-N3 thiosialyl donor was designed and synthesized, based on which a new sialylation protocol was established. In comparison to conventional sialylation methods, the new protocol exhibited obvious advantages, including excellent α-stereoselectivity in the absence of a solvent effect, broad substrate scope encompassing the challenging sialyl 8- and 9-hydroxy groups of sialic acid acceptors, flexibility in sialoside derivative synthesis, high temperature tolerance and easy scalability. In particular, the applicability to the synthesis of complex and bioactive N-glycan antennae when combined with the MPEP glycosylation protocol via the “latent-active” strategy has been shown. Mechanistically, the excellent α-stereoselectivity of the novel sialylation protocol could be attributed to the dramatic electron-withdrawing effect of the protonated Pic groups, which was supported by control reactions and DFT calculations.
5-azido derivatives of neuraminic acid - Synthesis and structure
Schneider, Regine,Freyhardt, Clemens C.,Schmidt, Richard R.
, p. 1655 - 1661 (2007/10/03)
Benzyl sialoside 1 was transformed into the corresponding 5-azido derivative 4 by N-nitrosation of the 5-acetylamino group and treatment with base followed by hydrazoic acid or, alternatively, by N,O-deacetylation followed by diazo group transfer to the amino moiety by means of TfN3. Regioselective 4-O-acetylation and introduction of the MPM group at 9-O afforded glycosyl acceptor 11. N,O-Deacetylation of ethyl 2-thiosialoside 13 afforded 14 which, after diazo group transfer to the amino group, furnished 5-azido derivative 16, which can serve as a sialyl donor. Activation of the ethylthio leaving group in the absence of an acceptor afforded 2,3-dehydro derivative 17. Regioselective 4-O-acetylation and 9-O-benzylation furnished glycosyl acceptor 22. An X-ray analysis was obtained from crystals of the 7,8,9-O-unprotected intermediate 21.
