The discovery that traditional silver(I)-oxide-promoted glycosidations of glycosyl bromides (Koenigs–Knorr reaction) can be greatly accelerated in the presence of catalytic trimethylsilyl trifluoromethanesulfonate (TMSOTf) is reported. The reaction conditions are very mild that allowed for maintaining a practically neutral pH and, at the same time, providing high rates and excellent glycosylation yields. In addition, unusual reactivity trends among a series of differentially protected glycosyl bromides were documented. In particular, benzoylated α-bromides were much more reactive than their benzylated counterparts under these conditions.

Advances in synthetic carbohydrate chemistry have dramatically improved access to common glycans. However, many novel methods still fail to adequately address challenges associated with chemical glycosylation and glycan synthesis. Since a challenge of glycosylation has remained, scientists have been frequently returning to the traditional glycosyl donors. This review is dedicated to glycosyl halides that have played crucial roles in shaping the field of glycosciences and continue to pave the way toward our understanding of chemical glycosylation.

Who designed the cover?We have been collaborating with Fabia D'Amore-Krug, at alented artist who teaches art therapy.F or our previous covers, all we had to do is describe the general outcome of our article in lay terms, and she would immediately come up with an image in her head. The fact that this reaction can now proceed much faster was shown by Fabia with two cars:o ld and slow versus new and fast. She quickly sketched the image of the two cars racing each other and came up with other ideas, such as gas stations, St. Louis skyline, etc. Fabia's initial sketch was done in pencil and then she created her final image in beautiful watercolor.

Examples include all common hexoses, aminosugars, sialic acids, and disaccharides.