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

摘要

Dimeric arylbicycloheptylpalladium halide complexes of type 1 undergo selective alkylation at the aromatic site by reaction with allyl, styryl, and benzyl bromides (RBr) via hexahydromethanopalladafluorenes (2). Ring closure of the resulting palladium complex (7) on sp(2) and sp(3) C-H bonds of a suitable R group then occurs with formation of hexahydromethanophenanthrene or hexahydromethanofluorene derivatives. Alternatively, substituted arenes derived from bicycloheptene deinsertion are formed. In some cases the latter can be obtained in substantial amounts when methyl isonicotinate is used as ligand. [References: 33]