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

3.2 Results and Discussion
3.2.1 Reactions of Allyl Chlorides with Palladium
Scheme 3.9 Reaction of 2-chlorobut-3-enyl benzoate with Pd(PPh3)4
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Chapter Three
The synthesis of palladium allyl complexes from allylic chlorides was first attempted using
the method outlined by Kurosawa. Here an excess of 2-chlorobut-3-enyl benzoate (108)
was reacted with Pd(PPh3)4 in anhydrous DCM at room temperature. However, 1 H NMR
spectroscopy revealed that although the desired product was formed, considerable quantities
of allylic chloride starting material and triphenylphosphine were also present. Therefore an
alternative synthetic route was considered. Following Bäckvall’s protocol, [35] equimolar
amounts of 2-chlorobut-3-enyl benzoate (108) and Pd(dba)2 were mixed in DMSO and the
reaction mixture was stirred at room temperature for 3 hours. The product was extracted
with chloroform, washed with water, dried over magnesium sulphate, followed by removal
of solvent and drying in vacuo to afford the crude product as a yellow solid. 1 H NMR
spectroscopy showed that only dba and product were present. The crude product was then
purified by column chromatography [DCM:hexane (70:30)] to afford the product, Bis[�-
chloro-bis(butenyl-(1,2,3-�)-benzoate]dipalladium (125) as a bright yellow solid in 71 %
yield.
Scheme 3.10 Synthesis of (125)