Catalysis by gold(I) and gold(III):: A parallelism between homo- and heterogeneous catalysts for copper-free Sonogashira cross-coupling reactions

(Chemical Equation Presented) Zero, one, or three? The role of Au 0, AuI, and AuIII cations in the heterogeneous gold catalyst Au/CeO2 was investigated with the copper-free Sonogashira cross-coupling reaction of iodobenzene and phenyl acetylene (see picture). Reactions carried out under both heterogeneous and homogeneous conditions using distinct Au0, AuI, and AuIII species reveal that AuI is the active species for the cross-coupling reaction. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.