The Effect of Chloride Ions on the Mechanism of the Oxidative Addition of Cyclic Allylic Carbonates to Pd0 Complexes by Formation of Neutral[(η1‐allyl)PdClL2] Complexes

Abstract

AbstractThe reversible oxidative addition of a cyclic allylic carbonate cis‐1 to palladium(0) complexes ligated by PPh3 is affected by chloride ions in DMF or chloroform. In the presence of chloride ions, the oxidative addition may become irreversible and the rate of isomerization of cis‐1 to trans‐1 is slowed down. This is a consequence of a slower isomerization of the cationic complex [(η3‐allyl)Pd(PPh3)2]+ (cis‐2+) to trans‐2+ due to the formation of neutral [(η1‐allyl)PdCl(PPh3)2] (cis‐3/trans‐3) complexes. Such complexes are formed instead of the cationic cis‐2+ and trans‐2+ whatever the source of chloride ions, i.e., whether voluntarily added to the cationic complexes cis‐2+ and trans‐2+, voluntarily added in the oxidative addition of cis‐1 with Pd0 complexes ligated to PPh3, or introduced in the dimeric complexes [(η3‐allyl)Pd(μ‐Cl)]2 (cis‐5/trans‐5). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)