5-Fluoro derivatives of 4-epi-isofagomine as d-galactosidase inhibitors and potential pharmacological chaperones for GM1-gangliosidosis as well as Fabry's disease

•The first synthesis of 5-fluoro-isoimino sugars.•The tertiary fluorine substituent is located at the branching point.•Compounds exhibit improved α-galactosidase inhibition.

Electrophilic fluorination of an exocyclic methoxymethylene enol ether derived from N-tert-butyloxycarbonyl-1,5-dideoxy-1,5-imino-3,4-O-isopropylidene-d-erythro-pent-2-ulose (11) provided the 5-fluoro derivative of the powerful β-galactosidase inhibitor 4-epi-isofagomine (8). This structural alteration, in combination with N-alkylation, led to considerably improved α-galactosidase selectivity. New compounds may serve as leads en route to new pharmacological chaperones for Fabry's disease.

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