Journal Publications

Julian G. Knight, Simon Doherty, Edward G. Robins, Tom H. Scanlan, Paul A. Champkin, and William Clegg, J. Am. Chem. Soc., 2001, 123, 5110.

Abstract: A new class of 1,4-bis(diphenylphosphino)-1,3-butadiene bridged diphosphine (NUPHOS) forms highly active catalysts for palladium mediated cross couplings. The diphosphine 1,4-bis(diphenylphosphino)-1,2,3,4-tetraphenyl-1,3-butadiene (1,2,3,4-Ph₄-NUPHOS), has been prepared by the reductive coupling of diphenylacetylene with Negishi’s reagent, followed by transmetallation of the resulting zirconacyclopentadiene with CuCl prior to quenching with diphenylchlorophosphine. Palladium complexes of these new diphosphines are highly active for the cross coupling of bromobenzene and sec-butylmagnesium bromide. In fact, catalysts based on 1,2,3,4-Ph₄-NUPHOS are approx. thirty times more active than the most active catalyst reported to date for this coupling.