Metal-directed stereoselective functionalization of alkenes in organic synthesis

The critical role of metals in π-face selective alkene functionalizations is exemplified by Diels-Alder reactions, osmylations, hydrogenations, conjugate additions (hydride, organocopper reagents, alkylmagnesium halides) of N-enoyl-bornane-10,2-sultams as well as by protonations, alkylations and aldolizations of “enolates” derived from the same auxiliary. In extension of the magnesium-ene process catalytic intramolecular palladium-ene reactions are presented. Thus, Pd(dba)2/PPh3- or Pd(PPh)3-catalyzed stereoselective cyclizations of acetoxy-2,7(8)-dienes gave 1-vinyl-2-methylene- or 1,2-divinyl-substituted cyclopentanes (or cyclohexanes) consistent with a cis-insertion/β-elimination process