Synthesis of Biaryl Diphosphines via a Stepwise Regioselective Double Diels−Alder Cycloaddition−Elimination Sequence: Efficient Ligands for the Palladium-Catalyzed Amination of Aromatic Bromides

Tropos and atropos biaryl diphosphines have been prepared in a stepwise, highly regioselective double Diels−Alder cycloaddition−elimination sequence between 1,4-bis(diphenylphosphinoyl)buta-1,3-diyne and various 1,3-dienes; the unsymmetrical phosphine 2,6′-bis(diphenylphosphino)-2′-methoxy-1,1′-biphenyl prepared using this approach forms an efficient catalyst for the amination of a range of aromatic bromides, giving conversions that rival those obtained with its BIPHEP counterpart.