Alkyne Reactions with Arylpalladium Compounds

Cyclopalladated N, N-dimethylbenzylamine trifluoromethanesulfonate reacts with diphenylacetylene to form a benzofulvene derivative, VIII. New complexes of two alkyne units with one cyclopalladated chloro dimer were prepared including a bis(dimethyl acetylenedicarboxylate)-cyclopalladated dimethylbenzylamine product and a 3-hexyne-cyclopalladated [(dimethylamino)methyl]ferrocene complex. Several 3:1 alkyne to aryl halide compounds have been formed catalytically from aryl iodides or bromides and alkynes. They are pentaalkylcyclopentadiene derivatives II. Methyl o-iodobenzoate with some alkynes yields isocoumarin derivatives. In some cases hexacyclic or tetracyclic 4:2 alkyne to aryl halide products are formed, also. Mechanisms are suggested to explain these and related reactions.