The asymmetric synthesis of a new pyrrolidine intermediate and a preceding amino triol derivative was accomplished using Crimmins' modified Evans aldol reaction as the key step. The synthetically useful pyrrolidine intermediate is expected to serve as the immediate precursor of biologically important pyrrolizidine alkaloids (-)-isoretronecanol and (-)-cremastrine. In addition, the amino triol subunit acts as a useful intermediate for the synthesis of oxocane heterocycles.