Studies on the sialylation of galactoses with different C-5 modified sialyl donors
摘要:
Synthetic sialylated glycans provide useful tools to study carbohydrate-mediated biological recognition; however chemical sialylation is the most challenging practice in preparative carbohydrate chemistry, which is often associated with low yields and poor stereoselectivity. Herein, we conducted extensive studies on sialylation with five types of 5-N-modified sialyl donors and four types of galactosyl acceptors. Our studies have shown that a good combination between the donor and the acceptor seems necessary to achieve high yield and stereoselectivity. None of the donors or acceptors showed 'universal' utility toward the sialylation reaction. (C) 2012 Elsevier Ltd. All rights reserved.
The First Total Synthesis of 6-Sulfo-de-N-acetylsialyl Lewisx Ganglioside: A Superior Ligand for Human L-Selectin
摘要:
Originally discovered as a minor by-product of 6-sulfo-N-acetylsialyl Lewis(x) , the de-N-acetylated form 1 is a superior L-selectin ligand to the N-acetyl form. To substantiate the extraordinary reactivity of 1, it was synthesized for the first time and its binding to L-selectin investigated. Compound 1 and related structures may be high-affinity endogenous ligands for L-selectin that are involved in the interaction of leukocytes with the vascular endothelium.