TfO - ···H-O-H Interaction-Assisted Generation of a Silicon Cation from Allylsilanes: Access to Phenylallyl Ferrier Glycosides from Glycals.

We demonstrate here that the strained and bulky protonated 2,4,6-tri- tert -butylpyridine (TTBPy) triflate salt serves as a mild and efficient organocatalyst for the diastereoselective C -Ferrier glycosylation of various glycals. The importance of the role of the 1/2 H 2 O molecule trapped in the catalyst has been disclosed. The mechanism of action involves unique anionic triflate and H 2 O hydrogen-bond interactions that assist the activation of allylsilanes, providing unprecedented access to diastereoselective phenylallyl Ferrier glycosides.