Synthesis of rare carbohydrates and analogues starting from enantiomerically pure 7-oxabicyclo[2.2.1]heptyl derivatives ("naked sugars")

Recent applications of the "naked sugar" methodology are reviewed. General methods have been developed to transform enantiomerically pure 7-oxabicyclo [2.2.1]heptyl derivatives into rare monosaccharides, carbasugars, into a ne w doubly-branched imino-dideoxyalditol (iminosugar), into long-chain carboh ydrates, C-disaccharides, imino-C-disaccharides and new polyhydroxylated qu inolizidines. The methods allow to prepare both enantiomers of a given targ et with the same ease. Predictable high stereoselectivity of the reactions of the bicyclic chirons adds to the flexibility of the approach that can le ad to a large molecular diversity.