Efficient Synthesis of Isofagomine and Noeuromycin

Starting from D‐arabinose the synthesis of the very strong glycosidase inhibitors isofagomine (2) and noeuromycin (3) was achieved in six and seven steps, respectively. Keystep in the reaction sequence is the application of an efficient C‐4 oxidation method to benzyl α‐D‐arabino‐pyranoside. Subsequent Henry reaction of the obtained aldoketose with nitromethane provided the required branched carbohydrate precursors, which gave access to 2 and 3 in 17–21 % overall yield. The highly potent glycosidase inhibitors isofagomine and noeuromycin were synthesized starting from D‐arabinose (see scheme) in six and seven steps, respectively. The C‐glycosidic linkage was obtained through the Henry reaction to provide the branched carbohydrate precursor.