Halophilic Metal Salts for the Cooperatively Catalyzed Activation of Thioglycosides

Reported herein is the expansion of the cooperatively catalyzed Koenigs-Knorr glycosylation reaction, known as "the 4K reaction". It has recently been discovered that thioglycosides can be activated in the presence of molecular iodine, a metal salt, and an acid additive. The mechanistic studies proposed the interaction of anomeric sulfur with thiophilic iodine. The resulting complex is stable until the halophilic silver salt and acid additive are added. This discovery has opened a new avenue for the development of new halophilic promoters that do not activate thioglycosides in the absence of iodine. Presented herein is the discovery of bismuth(III) triflate as an efficient activator of thioglycosides via the 4K reaction pathway.