Koenigs–Knorr Glycosylation Reaction Catalyzed by Trimethylsilyl Trifluoromethanesulfonate.

Singh, Yashapal; Demchenko, Alexei V.

The discovery that traditional silver(I)‐oxide‐promoted glycosidations of glycosyl bromides (Koenigs–Knorr reaction) can be greatly accelerated in the presence of catalytic trimethylsilyl trifluoromethanesulfonate (TMSOTf) is reported. The reaction conditions are very mild that allowed for maintaining a practically neutral pH and, at the same time, providing high rates and excellent glycosylation yields. In addition, unusual reactivity trends among a series of differentially protected glycosyl bromides were documented. In particular, benzoylated α‐bromides were much more reactive than their benzylated counterparts under these conditions. Fast glycosylations! Effective reaction conditions for a rapid Koenigs–Knorr glycosylation catalyzed by trimethylsilyl trifluoromethanesulfonate (TMSOTf) are reported. The glycosylation products were formed in minutes and the neutral activation conditions were compatible with many protecting and leaving groups. An unusual reactivity trend according to which benzoylated α‐bromides are much more reactive than their benzylated counterparts was demonstrated. The reaction mechanism was also investigated.

GLYCOSYLATION; SULFONATES; BROMIDES; REACTION mechanisms (Chemistry); CARBOHYDRATES

Chemistry - A European Journal, 2019, Vol 25, Issue 6, p1461

0947-6539

Academic Journal

10.1002/chem.201805527