Synthesis and Comparison of the Reactivity of Allyl Fluorides and ...

4.2.2 Reactions of palladium cationic complexes with dimethyl malonate anion
103
Chapter Four
Having reacted the Pd (II) chloro-bridged dimers with both pentane-2,4-dione and dimethyl
malonate, it was decided to react the palladium cationic complexes synthesised in Chapter
Three with dimethyl malonate anion. This would enable a one pot reaction to be conducted
as opposed to forming and isolating the Pd �-allyl complex prior to nucleophilic attack. It
would also enable a comparison of the reactivity to be made between neutral Pd �-allyl
compounds and cationic palladium allyl complexes.
However, first it was necessary to investigate whether the palladium cationic complexes
synthesised from 2-chlorobut-3-enyl benzoate (108) and 2-fluorobut-3-enyl benzoate (75)
would afford the same product or different products when reacted with sodium dimethyl
malonate.
Scheme 4.7 Synthesis of (151) from (108) and (75)
Therefore, (75) and (108) were both reacted with sodium dimethyl malonate following the
method outlined by Gouverneur et al. [32] Firstly, the catalyst was prepared by stirring
[Pd(C3H5)Cl]2 with PPh3 in anhydrous DCM. After which (75)/(108), sodium dimethyl
malonate and 15-crown-5 were added. The reaction mixture was left to stir overnight, after
which the reaction mixture was quenched with water, the aqueous phase extracted with
diethyl ether, the organic phases dried over MgSO4 and concentrated in vacuo. Analysis by
1 H NMR spectroscopy of the crude products, showed that both (75) and (108) had formed
the same product, which was purified by column chromatography [hexane: ethyl acetate
(70:30)], affording the same isolated product (151) in moderate yields (46 and 40 %), which
was characterised by 1 H and 13 C NMR spectroscopy and mass spectrometry.
Consequently, as the same product was formed via the palladium cationic complex
synthesised from 2-fluorobut-3-enyl benzoate (75) and 2-chlorobut-3-enyl benzoate (108).
Subsequent nucleophilic reactions were conducted with palladium cationic complexes
synthesised from (108) since the chlorinated allyl substrates can be synthesised more
readily. In order to investigate whether substituents on the benzene ring influence the