Influence of 4,6‐ <i>O</i> ‐Benzylidine Towards α‐Galactosylation, Overcoming Neighbouring Group Participation Effect: An Unanticipated Observation With Viable Solution

The construction of β‐glycosidic linkages with the assistance of neighbouring group participation (NGP) during N ‐iodosuccinimide and trimethylsilyl trifluoromethanesulfonate‐mediated glycosylation reactions is considered one of the most reliable reactions. In this study, we demonstrated that the 4,6‐ O ‐benzylidine protection in the galactosyl thioglycoside donor can overshadow the NGP effect, furnishing the unexpected α ‐glycoside with a specific set of acceptors and donors. We synthesized an orthogonally protected galactosyl thioglycoside donor to overcome the unexpected stereoselectivity. The outcome revealed that the presence of 4,6‐ O ‐benzylidine protection on the donor moiety can alter the stereoselectivity during glycosylation in certain cases.