Glycosylation conditions

Karsten, U., Serttas, N., Paulsen, H., Danielczyk, A., and Goletz, S. (2004) Binding patterns of DTR-specific antibodies reveal a glycosylation-conditioned tumor-specific epitope of the epithelial mucin (MUC1). Glycobiology 14(8), 681-692. 

In model experiments several detailed studies of the solvolyses of glycosyl halide derivatives have been imdertaken 1.24,25) and have led to the conclusion that reaction usually occurs by way of an Sul mechanism (Walden inversions are frequently observed and Sn2 character is known to intrude imder some conditions, notably in solvents of low polarity and in the presence of strong nucleophiles), but no full understanding of the mechanisms of the reactions of these compounds under glycosylating conditions has been achieved. Instead, a realisation of the complex... 

Cleavage of trityl ethers is accomplished by acid hydrolysis. Use of the mono- or di-methoxy analogs increase the acid lability of the trityl ethers, but none of the trityl ethers is stable enough to withstand normal glycosylation conditions, and they are only used as intermediates to construct building blocks to be used in subsequent oligosaccharide syntheses. 

Wei, G, Gu, G, Du, Y, Silver triflate. A mild alternative catalyst for glycosylation conditions using trichloroacetimidates as glycosyl donors, J. Carbohydr. Chem., 22, 385-393, 2003. 

The NSEC group is stable to glycosylation conditions using glycosyl phosphates, and it is not affected under deprotection conditions that facilitate the removal of Lev, Fmoc, allyl, and PMB groups. For ester-type protecting groups selective deprotection in the presence of NSEC derivatives is not possible. 

In addition to the importance of linkers described above, the precise choice of protecting groups is also an important factor for oligosaccharide assembly to be successful on solid-supports. Utilization of protecting groups that are stable under glycosylation conditions but can... 

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