Synthesis of the diphenylacetylene-based, tetra-amine ligand 1,2-bis(3,5-bis[(dimethylamino)methyl]phenyl)acetylene by palladium-catalysed cross-coupling: isolation and crystal structure of the catalyst trans-(3,5-bis[(dimethylamino)methyl]-phenyl)bis(triphenylphosphine)palladium(II) iodide

Reaction of 3,5-bis[(dimethylamino)methyl]phenyl iodide with 3,5-bis[(dimet hylamino)methyl]phenylacetylene in diethylamine in the presence of bis(trip henylphosphine)palladium(II) dichloride (3.6 mol%) and copper(I) iodide (3. 0 mol%) gave 1,2-(bis(3,5-bis[(dimethylamino)methyl]phenyl)acetylene (1) in 82% yield. The palladium catalyst was recovered in 93% yield as trans-(3,5 -bis[(dimethylamino)methyl]phenyl)bis(triphenylphosphine)palladium(II) iodi de (2). The crystal structure of 2 shows that the coordination geometry of the palladium is distorted square-planar. No inter- or intramolecular inter actions between the N-donor atoms and the Pd are observed. (C) 2000 Elsevie r Science S.A. All rights reserved.