Reaction of Palladium and Platinum Complexes Bearing α,β-Unsaturated Carbonyl Compounds with Carbon Electrophiles: Control over Site of Electrophilic Attack, Oxygen or Metal

The reaction of (η2-CH2CHCHO)ML2 (M = Pd, Pt; L = PPh3, L2 = DPPF) with methyl
triflate gave η3-methoxyallyl complexes [(η3-CH3OCHCHCH2)ML2][OTf]. X-ray diffraction
analysis on [(η3-CH3OCHCHCH2)M(dppf)][OTf] (M = Pd, Pt) showed a distorted η3-allyl
structure. The enone complexes (η2-CH2CHCOCH3)M(PPh3)2 also reacted with methyl
triflate to give [(η3-CH3OC(CH3)CHCH2)M(PPh3)2][OTf]. It was proposed that these complexes
were formed by the direct electrophilic attack of methyl triflate at the carbonyl oxygen of
the enal or enone ligand on the palladium and platinum. In fact, no insertion of acrolein
into the platinum−methyl bond of the separately isolated methylplatinum complex proceeded.
On the other hand, methyl iodide underwent oxidative addition with zerovalent enal or enone
complexes to give methylmetal complexes concomitant with dissociation of an enal or enone
molecule.