New accesses to L-iduronyl synthons

(PhS)(3)CLi adds with a total L-ido selectivity onto 3-O-benzyl-1,2-O-isopropylidene-alpha-D-xylo-dialdose 2, opening the way to the most efficient preparation of 1,2,4-tri-O-acetyl-3-O-benzyl-L-iduronyl synthon 8. Alternatively, in view of combinatorial syntheses, aldehyde 2 allows a good access to vinylic L-ido and D-gluco synthons which may be converted into uronic acid by a sequence involving a new aldehyde oxidation by m-CPBA in aqueous solution. (C) 2000 Elsevier Science Ltd. All rights reserved.