Ferrocenyl iminophosphine ligands in Pd-catalysed Suzuki couplings

A mixture of Pd-2(dba)(3)/{eta-C5H4CH=N[CH(CH3)(Nap)]}Fe[eta-C5H4P(Bu-t)(2)] efficiently catalyzes the Suzuki reactions of a variety of bulky aryl halides and aryl- and alkyl-boronic acids, affording the desired cross-coupling biaryl products in quantitative isolated yields under mild conditions and at low (1 x 10(-6) -1 mol%) Pd loadings. Spectroscopic (NMR & ESI) analysis of the mixture of Pd-2(dba)(3), the hybrid [P,N] ligands, and aryl halides revealed different structural forms of oxidative addition products that are dependent on the substituent on the imino nitrogen. (C) 2011 Elsevier B.V. All rights reserved.