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
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 axiallylinked2-deoxysaccharides (9–17,30,32,33). Application of this method for the synthesis of disaccharide fragment 28 of avermectin is also
A facile and direct method for the construction of 2'-deoxy-beta-N-glycosidic linkages in 2'-deoxyribonucleoside synthesis has been developed by using 3-(3,4,5-trimethoxybenzoyl)-protected 2-deoxyribofuranosyl diethyl phosphites as a glycosyl donor in the presence of trimethylsilyl triflate, wherein coupling reactions with silylated pyrimidine bases have been found to exhibit beta-selectivities up to 96%.