Selective fowler reductions: asymmetric total syntheses of isofagomine and other 1-azasugars from methyl nicotinate.

[figure: see text] An efficient, high-yielding strategy has been developed for the asymmetric synthesis of 1-N-iminosugars (1-azasugars), a new class of glycosidase inhibitors with promising biomedical applications. A highly regioselective procedure for the 1,2-reduction of substituted pyridines was employed to transform methyl nicotinate into several representative 1-azasugars.