1,3-Dipolar Cycloadditions to Unsymmetrical Ketone-Derived Chiral Stabilized Azomethine Ylides: Strategies for the Synthesis of Highly Substituted Amino Acids - Aldous, David J; Drew, Michael G B; Draffin, William N; Hamelin, Estelle M-N; Harwood, Laurence M; Thurairatnam, Sukanthini (Synthesis, 2005)