Studies on the Lithiation of Hydroxypyrrolidines: Synthesis of Polyhydroxylated Pyrrolidines via Chiral Enecarbamates

The chiral endocyclic enecarbamate 14 has been ob- tained by deprotonation–elimination from the N-Boc pyrrolidine 5 (or its racemic counterpart from 15). Efficiently stereocontrolled epoxidation–methanolysis of 14 afforded a-alkoxy carbamates, which undergo completely stereoselective nucleophilic substitu- tions to give trisubstituted dihydroxypyrrolidines