Abstract
The activation of 2‐azido‐2‐deoxy Tn and TF thioglycosyl donors by the powerful thiophilic promoter system Ph2SO/Tf2O has been investigated. Glycosylation of an Fmoc‐protected threonine derivative gave 1,2‐cis glycosides in high yields and excellent stereoselectivities. The galactosylation of phenyl 2‐azido‐4,6‐O‐benzylidene‐2‐deoxy‐1‐thio‐β‐D‐galactopyranoside was achieved in high yield and without orthoester formation using a trichloroacetimidate donor carrying a 2‐O‐(2,5‐difluorobenzoyl) group. The anomeric thiophenyl group of the constructed TF disaccharide could directly be activated by the van Boom promotor for the glycosylation of a threonine derivative.
* Dedicated to the memory of Professor Jacques H. van Boom
Acknowledgements
The authors are grateful for financial support from the National Cancer Institute of the National Institutes of Health (Grant No. RO1 CA88986).
Notes
* Dedicated to the memory of Professor Jacques H. van Boom