Terpene Amine Synthesis via Palladium-Catalyzed Isoprene Telomerization with Ammonia

Article abstract of DOI:10.1021/jo00331a024

Isoprene and dry ammonia could be converted in a catalytic process in good yields into a mixture of primary, secondary, and tertiary terpene amines.Homogeneous catalysts formed from palladium acetylacetonate and tributyl phosphite showed the best activities and selectivities for the telomerization.Seven amines were isolated as the main products from the reaction mixture and were characterized by their spectral data.Tail-to-tail coupling of the isoprene units was predominant though under certain conditions α-linalylamine, which shows a head-to-tail structure, prevailed.The product distribution could be controlled by cocatalysts and reaction parameters.The formation of primary terpene amines was favored by short reaction times and high ammonia/isoprene ratios.The proper choice of solvents and especially ligands is shown to be essential, and a strong dependence on the catalyst concentration was observed.A mechanism involving bridged binuclear palladium complexes as the active species is discussed.