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

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Chapter Four
substituents on the benzene ring do have an impact on the site of nucleophilic attack.
Consequently in order to fully understand why nucleophilic attack has occurred at the more
hindered carbon in (110) further synthetic work and possibly, modelling studies would need
to be conducted.
In the reaction of (112) with sodium dimethyl malonate the co-product dimethyl 2-allyl
malonate (154) was also isolated. This is formed as a result of excess sodium dimethyl
malonate reacting with the allyl from the [{Pd(C3H5)Cl}2] starting material (Scheme 4.8).
Scheme 4.8 Synthesis of (154)
Having reacted a variety of the derivatised allylic chlorides in a palladium catalysed reaction
with sodium dimethyl malonate, efforts were concentrated on reacting in situ formed
palladium cationic complexes with other carbon-based nucleophiles and sources of fluoride
ion.
4.2.3 Reactions of Pd cationic complexes with other carbon based nucleophiles
Having established the regioselectivity attained when (108) and (112) underwent
nucleophilic attack via their palladium cationic complexes, reactions were conducted with
other carbon-based nucleophiles in order to observe whether the same regioselectivity was
retained. The Shibata reagent; 1-fluoro bis(phenylsulfonyl)methane (140), is a novel
reagent for introducing the CH2F moiety into organic substrates. [14] Therefore this reagent
was utilised in reactions with (112) and (108), as once the corresponding product has
formed, the sulphonyl groups can be cleaved in order to yield the potentially valuable
fluoromethylated compounds.
The Shibata reagent, 1-fluoro bis(phenylsulfonyl)methane (140), was synthesised following
the literature protocol. A mixture of NaH and anhydrous THF was cooled to 0 °C and then
charged with bis(phenylsulfonyl)methane. A solution of Selectfluor in dry MeCN was
added dropwise and the reaction mixture was stirred for 3 hours at room temperature. Work
up of the crude product followed by purification via column chromatography [hexane: DCM
(20:80)] afforded the product (140) as a white solid in a moderate 58 % yield (Scheme 4.9).