Synthesis and Elimination of C‑3-Labeled Thiosialosides

The synthesis of C-3-labeled phenylthio sialic acid derivatives and an investigation of stereoselectivity in elimination reactions for the synthesis of 2,3-dehydro derivatives (glycals) is described. The experimental results are consistent with the existence of a conformational change and may be indicative of the intermediacy of an all-axial oxacarbenium ion

How O-Substitution of Sialyl Donors Affects Their Stereoselectivity

The profound effect of substituents at C-5 of glycosyl sialosides on their stereoselectivity is well-known although the exact nature of this effect is somewhat less understood. Presented herein is a comparative study of a range of novel sialyl donors with various O-substituents. It is demonstrated that O-substituents at C-4 and C-7 may also have a significant effect on the reactivity of sialyl donors and on the stereoselectivity of chemical sialylation