Visible-light-promoted O-glycosylation with indolylthio glycosides.

A novel method for the preparation of thioglycoside donors from d-glucose and 2-indolone was developed. This method is straightforward to operate and enables highly efficient catalysis under mild conditions. In addition, a method for O-glycosylation of thioglycosides with various alcohols using trifluoromethyl thianthrenium triflate (TT-CF3+TfO-) as an initiator and a visible light-induced photoredox catalysis method was also developed. The method is green, mild, easy to perform and does not require a neutralization step.