alpha-selective sialylations at -78 degrees C in nitrile solvents with a 1-adamantanyl thiosialoside.

David Crich, Wenju Li

Index: J. Org. Chem. 72 , 7794, (2007)

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Abstract

Novel 1-adamantanylthio sialosides were synthesized and coupled to acceptors under NIS/TfOH promotion conditions. These donors showed higher reactivity than the phenylthio sialosides and could be activated by NIS/TfOH in nitrile solvents at -78 degrees C to afford improved alpha-sialylations. With the N-acetyl-5-N,4-O-oxazolidinone-protected 1-adamantanylthio sialyl donor high alpha-selectivities could be achieved in the sialylations of both primary and sterically hindered secondary acceptors, including the important galactose 3-OH acceptors.