Catalytic hydroalkylation of olefins by stabilized carbon nucleophiles promoted by dicationic platinum(II) and palladium(II) complexes

The coordinated olefin in dicationic platinum(II) and palladium(II) complexes [M(PNP)(olefin)]-(SbF6)2 (M=Pt, Pd; PNP=2,6-bis(diphenylphosphinomethyl)pyridine; olefin=ethylene, propylene) reacts with β-dicarbonyl compounds (pentane-2,4-dione and methyl-3-oxobutanoate). If the proton released after the nucleophilic attack is trapped by a base, stable σ-alkyl derivatives [(PNP)M-CH2-CH(R)CH(Ac)COR0]SbF6 (R=H,Me;R0 =Me, OMe) are formed; otherwise theM-Cσ-bond can be cleaved by the proton, in the rate-determining step of a catalytic cycle that leads to the alkylated dicarbonyl compound.Theβ-diketone is intrinsically more reactive than theβ-ketoester, but in the catalytic reaction of the former an inhibition effect is observed in the case of the platinum catalyst.