Stereodivergent Methodology for the Synthesis of Complex Pyrrolidines

The intramolecular reaction of oxime ethers and cyclopropane diesters results in the diastereoselective formation of substituted pyrrolo-isoxazolidines which serve as precursors to the ubiquitous
pyrrolidine motif. A simple reversal of addition order of catalyst and substrate results in formation of two
discrete diastereomers in a highly selective and predictable manner. The adducts are prepared in excellent
yields from either enantiomer of an alkoxyamino-tethered cyclopropanediester, allowing efficient access to
highly substituted homochiral pyrrolidines.