One-pot glycosylation

One-pot procedure integrates several glycosylation steps into one synthetic operation to furnish the target oligosaccharide in a short period of time without 

SCHEME 3.28 Programmable one-pot synthesis of Globo-H. CIBn, o-chlorobcnz.yl NBz, 

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General Procedure for One-Pot Glycosylation Using Glycosyl Iodides 90 References 90... 

Hanessian and coworkers have used a one-pot glycosylation in their development of 2-pyridylcarbonate donors, which were found to be unstable to chromatography... 

Takahashi and coworkers described an effective sialylation method utilizing the N-Fmoc, N-Troc and N-trichloroacetyl-P-thiophenyl sialosides (Scheme 4.6d) [167]. It was found that the N-Troc derivative of N-acetylneuraminic acid performed better than the corresponding N-Fmoc derivative. An N-Troc P-thiosialoside was applied for the synthesis of glycosyl amino acids by one-pot glycosylation [167]. Importantly, it was found that the N-Troc protecting group could be converted into an acetamido moiety without causing racemization of the peptide. 

Scheme 5.70 Sequential, one-pot glycosylation using 1,2-anhydro sugars.

Common Anomeric Groups, Common Activators Both conformational and electronic factors have been exploited to obtain selectivity in one-pot glycosylations using common anomeric groups and activators. Selectivity results from differences in the stability of oxonium ion intermediate between the two prospective glycosyl donors. 

In 1993, the first of many reports of one-pot glycosylation reactions appeared. Raghavan and Kahne9 used TfOH (or triflic anhydride) to sequentially activate phenylsulfoxide glycosides that differed in their substitution pattern at the para... 

Building on the observations of Kahne and Takahashi, Chenault and Castro relied on the selective activation of an isopropenyl glycoside donor with TMSOTf, followed by subsequent activation of a second n-pentenyl glycoside with NIS/TESOTf.12 This one-pot glycosylation offers proof of the concept that Fraser-Reid s glycosides can be incorporated into one-pot syntheses. (See Scheme 11.7.)... 

By omitting the chromatographic purification step, 2-pyridylcarbonates can be used as glycosyl donors in one-pot glycosylations, resulting in high overall yields and reason-... 

Reactivity-Based One-Pot Glycosylation Fine-Tuning of Anomeric Reactivities... 

SCHEME 6.1 General scheme for reactivity-based one-pot glycosylation. 

To synthesize longer oligosaccharide sequences using the armed-disarmed one-pot glycosylation approach, more than two consecutive glycosylation reactions are often... 

One-Pot Glycosylation Based on Chemoselective Activation of Different Types of Glycosyl Donors... 

SCHEME 6.14 One-pot glycosylation based on chemoselective activation of different types of glycosyl donors. 

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