Enantiomeric carba-sugars, synthesis

All sixteen of the racemic carba-sugars predicted are known, as well as fifteen of the enantiomers. The most accessible starting-material for the synthesis of racemic carba-sugars is the Diels-Alder adduct of furan and acrylic acid, namely, e i o7-oxabicyclo[2.2.1]hept-5-ene-2-carboxylicacid (29). Furthermore, adduct 29 is readily resolved into the antipodes, (—)-29 and (+)-29, by use of optically active a-methylbenzylamine as the resolution agent. The antipodes were used for the synthesis of enantiomeric carba-sugars by reactions analogous to those adopted in the preparation of the racemates. 

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