| Abstract
| - The appropriately substituted 5-O-tosyl derivative (1), easily prepared from 1,2-O-isopropylidene-α-d-xylofuranose, serves as a useful precursor for the preparation of highly condensed cyclic carbohydrates.The synthesis involves a first cyclization of the 5-O-tosyl sugar derivative 1 to a highly reactive cyclicenamine, which subsequently undergoes the nucleophilic attack of a bifunctional reagent X(CH2)nZ in aregio- and stereospecific way. Finally, a spontaneous cyclization step allows the formation of astereochemically defined extra ring, fused to the sugar backbone. The functionalization and size of thisring can be varied by the proper choice of the bifunctional reagent. X-ray diffraction analysis and intensiveNMR studies with one of these carbohydrates were performed to highlight the strained nature of thesecompounds.
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