DIASTEREO- AND ENANTIOSELECTIVE CONSTRUCTION OF 6,7-DIOXABICYCLO[2.2.1]HEPTANE DERIVATIVES BY A DIRHODIUM(II)-CATALYZED INTRAMOLECULAR C-H INSERTION REACTION

The first diastereo- and enantioselective construction of bridged bicyclic ring systems by an intramolecular C-H insertion reaction is described. With dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate], Rh2(S-PTTL)4, the C-H insertion of alpha-alkyl-alpha-diazoesters containing an ethylene ketal moiety at the gamma-position provided methyl 6,7-dioxabicyclo[2.2.1]heptane-3-carboxylate derivatives with up to 95% ee and perfect diastereoselectivity.