Glycosidation of thioglycosides in the presence of bromine: mechanism, reactivity, and stereoselectivity

J Org Chem. 2012 Jan 6;77(1):291-9. doi: 10.1021/jo2019174. Epub 2011 Dec 21.


Elaborating on previous studies by Lemieux for highly reactive "armed" bromides, we discovered that β-bromide of the superdisarmed (2-O-benzyl-3,4,6-tri-O-benzoyl) series can be directly obtained from the thioglycoside precursor. When this bromide is glycosidated, α-glycosides form exclusively; however, the yields of such transformations may be low due to the competing anomerization into α-bromide that is totally unreactive under the established reaction conditions.