New pathways of site selective aromatic alkylation of palladium complexes:fragmentation to arenes vs. ring closure to hexahydromethano-fluorenes or -phenanthrenes

Dimeric arylbicycloheptylpalladium halide complexes of type 1 undergo selec tive alkylation at the aromatic site by reaction with allyl, styryl, and be nzyl bromides (RBr) via hexahydromethanopalladafluorenes (2). Ring closure of the resulting palladium complex (7) on sp(2) and sp(3) C-H bonds of a su itable R group then occurs with formation of hexahydromethanophenanthrene o r hexahydromethanofluorene derivatives. Alternatively, substituted arenes d erived from bicycloheptene deinsertion are formed. In some cases the latter can be obtained in substantial amounts when methyl isonicotinate is used a s ligand.