A Novel β-Directing Fructofuranosyl Donor Concept. Stereospecific Synthesis of Sucrose

Abstract

A new concept for the construction of β-d-fructofuranosides based on the idea of locking the anomeric CH2OH group to the α-side through an internal bridge to the 4-hydroxyl group is presented. Thioglycoside fructose donors containing an internal 1,4-O-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl) (TIPS) acetal bridge have been constructed and used in glycosylations with dimethyl(thiomethyl)sulfonium triflate (DMTST) as promoter. The couplings were stereospecific to give β-d-fructofuranosyl disaccharides in high yields. Using this approach, sucrose has been synthesized stereospecifically in 80% yield.