Cooperatively Catalyzed Activation of Thioglycosides with Iodine and Iron(III) Trifluoromethanesulfonate.

Reported herein is a further expansion of the cooperatively catalyzed Koenigs-Knorr glycosylation reaction, known as "the 4K reaction". It has been discovered that molecular iodine, along with a metal salt and an acid additive, can activate thioglycosides. Previous mechanistic studies showed the interaction of the anomeric sulfur with thiophilic iodine; this complex is stable until the halophilic metal salt and the acid additive are added. This new avenue has allowed for the investigation of halophilic promoters that would not activate thioglycosides without iodine. Presented herein is the recent discovery of iron(III) triflate as an efficient activator of thioglycosides via the 4K reaction pathway.