6-Diphenylphosphino-2,2 -bipyridine, reaction

It has been found that the use, as ligands, of electron-poor phosphines, such as 1,1 -bis(diphenylphosphino)ferrocene, enhances yields ill the palladium-catalysed reaction of aiyl bromides with sodium phenoxides to yield diaryl ethers.87 Palladium-catalysed coupling of ethynylated derivatives of bipyridine or terpyridine with the corresponding bipyridine or terpyridine hahdes or triflates has been used in the synthesis of preorganized polytopic ligands.88... 

Copper(I)-catalyzed amination of iodobenzene with aniline in the presence of KO-t-Bu as base was described by Don and co-workers [56] (Scheme 22.12). They reported the use of the [Cu2(p-I)2(L)2] (L = l,2-bis(diphenylphosphino)-c/oi 0-carborane(12) (1)) catalyst, which showed a conversion of the amine of 58%, compared to no significant conversion without ligand 1. The conversion is in the range of the reaction of copper(I) iodide in the presence of 2,2 -dithiobis(5-nitropyridine) but lower than that of the 2,2 -bipyridine ligand [57]. It was postulated that the reaction proceeds via an insertion of the copper(I) species into the carbon-halogen bond as the initial step. 

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