A study of silver (I) perchlorate as an effective promoter for chemical glycosylation with thioimidates and thioglycosides

It has been previously acknowledged that perchlorate salts may be beneficial for the formation of 1,2-cis glycosides. Here, we demonstrate the effectiveness of silver (I) perchlorate as a powerful promoter of glycosyl thioimidate activation. Improved 1,2-cis selectivity was obtained, compared against that obtained with other silver (I) salts, including commonly-used triflate. The use of a combination of silver (I) perchlorate and methyl sulfenyl bromide to activate thioglycosides was also investigated. The cooperative use of these activation protocols was applied to a one-pot, two-step sequential activation, using thioimidate and thioglycoside building blocks.