Unprecedented oxidation of a phenylglycinol-derived 2-pyridone: enantioselective synthesis of polyhydroxypiperidines.

[reaction: see text]. The phenylglycinol-derived 2-pyridone 1 undergoes m-CPBA oxidation steroselectively leading to the chiral nonracemic unsaturated bicyclic hydroxylactam 2, from which the enantioselective synthesis of (3R,5R)-3,4,5-trihydroxypiperidine (16) and the formal synthesis of the azasugar epiisofagomine are described. The enantioselective synthesis of (S)-N-Boc-3-hydroxypiperidine and (3R,4S)-3,4-dihydroxypiperidine is also reported.