Stereoselective synthesis of α-linked 2-deoxysaccharides and furanosaccharides by use of 2-deoxy 2-pyridyl-1-thio pyrano- and furanosides as donors and methyl iodide as an activator

Abstract A practical and highly stereoselective glycosidation methodology is described, where anomeric mixture of 2-deoxy 2-pyridyl-1-thiopyranoside donors ( 1–3, 27 ) have been coupled with several sugar alcohols ( 4–8,29,31 ) on activation by methyl iodide to obtain axially linked 2-deoxysaccharides ( 9–17,30,32,33 ). Application of this method for the synthesis of disaccharide fragment 28 of avermectin is also described. Utility of this method is also shown by use of 2-pyridyl-1-thiofuranosides ( 34–36 ) as donors to prepare α-linked furnaosides ( 42–51 ).