1,6-Anhydro-β-D-glucopyranose derivatives as glycosyl donors for thioglycosidation reactions

Abstract

1,6-Anhydro derivatives of D-glucopyranose, maltose, and maltotriose reacted at room temperature with trimethylsilylated benzenethiol (2) and cyclohexanethiol (3) in the presence of zinc iodide (Znl₂) or trimethylsilyl triflate (TMSOTf), giving the corresponding thioglycosides with predominance of one anomer in high yield. 1,6-Anhydro-2,3,4-tri-O-benzyl-β-D-glucopyranose (1) condensed with a more complex thiol derivative, methyl 2,3,6-tri-O-benzyl-4-thio-4-S-trimethylsilyl-α-D-glucopyranoside (19), to give the 4-thiomaltose derivative (20), whereas no condensation took place between the 1,6-anhydro disaccharide homologue (21) and thiol derivative (19). The difference in reactivity between 1,6-anhydro mono- and di-saccharides was utilized for a specific cross-coupling reaction.