Stereodivergent Approach to Both C2,8a-syn and C2,8a-anti Relative Stereochemical Manifolds in the Lepadin Family via a TiCl4-Promoted Aza-[3+3] Annulation - Li, Gang; Carlson, Lauren J.; Sagamanova, Irina K.; Slafer, Brian W.; Hsung, Richard P.; Gilardi, Claudio; Sklenicka, Heather M.; Sydorenko, Nadiya (Synthesis, 2009)