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

2.2.2.1 Synthesis of Allylic Alcohols
2.2.2.1.1 Synthesis of 1-(Benzyloxy)but-3-en-2-ol (39)
Scheme 2.22 Synthesis of (98)
60
Chapter Two
Allylic alcohol (98) was synthesised following Trost’s [56] protocol; benzyloxyacetaldehyde
was added dropwise to a solution of vinylmagnesium bromide (1.1 equivalents) in THF,
causing the temperature to rise to 60 °C. The reaction mixture was refluxed for 30 minutes,
after which, cooling, aqueous workup, drying over magnesium sulphate and removal of
solvent in vacuo yielded the crude product. Analysis by 1 H NMR spectroscopy of the crude
reaction mixture revealed conversion to product to be 91 %. Purification by column
chromatography [hexane: ethyl acetate (80:20)] afforded the desired product in 81 % yield
as a yellow oil.
2.2.2.1.2 Synthesis of 2-hydroxybut-3-enyl benzoate and related Allylic Alcohols
The protocol by Ziegler, [57] was utilised in the synthesis of the benzoyl-derivatised allylic
alcohols by reaction of the appropriate benzoyl chloride with but-3-ene-1,2-diol. Products
were obtained in moderate yields (40 - 66 %), either as oils or as white solids (Scheme 2.23)
(Table 2.14).
Scheme 2.23 General reaction scheme for synthesis of (100-105)
(For a definition of R see Table 2.14)