New Approaches to the Stereoselective Synthesis of Carbohydrates

Abstract

In these years, much interest has been focused on the synthesis of monosaccharides starting from the simple organic molecules, with the development of various highly stereoselective carbon-carbon bond forming reactions of acyclic system. And, recently, convenient syntheses of a variety of monosaccharides are reported using 2, 3-O-isopropylidene-D-glyceraldehyde as 3-carbon building block. Further, a new and potentially useful chiral 4-carbon building block for the L-sugar, 4-O- benzyl-2, 3-O-isopropylidene-L-threose are prepared starting from L-tartaric acid and biologically important L-sugars are also successfully synthesized.
Several new glycosylation reactions, which proceed under mild reaction conditions with high stereoselectivity, are exploited; namely, i) the glycosyl fluoride method, ii) the glycoside synthesis by the stereoselective internal cyclizations, and iii) by the direct introduction of alkoxy group to α-position of keto function of sugar.