Synthesis and characterization of tris{2-(N,N-bis(diphenylphosphino) aminoethyl} amine derivatives: Application of a palladium(II) complex as a pre-catalyst in the Heck and Suzuki cross-coupling reactions

The polydendate bis(phosphino)amine, tris{2-(N,N-bis(diphenylphosphino)aminoethyl}amine 1 has been prepared in a single step from the reaction of tris(2-aminoethyl)amine with six equivalents of PPh2Cl in the presence of NEt3 in THF. Oxidation of 1 with aqueous H2O2, elemental sulfur or grey selenium gave the corresponding oxide, sulfide or selenide derivatives. [{(P(E)Ph2)2NCH2CH2}3N] (E: 2a O, 2b S, 2c Se), respectively. Reaction of [{(PPh2)2NCH2CH2}3N] with 3 equiv. of PdCl2(cod) or PtCl2(cod) gave the corresponding chelate complexes, [Pd3Cl61] or [Pt3Cl61]. The new compounds were fully characterized by NMR, IR spectroscopy and elemental analysis. The catalytic activity of the Pd(II) complex was tested in the Suzuki coupling and Heck reactions. The Pd(II) complex catalyzed the Suzuki coupling and Heck reaction affording biphenyls and stilbenes, respectively, in high yields.