Condensation of dibromide (I) with allyl alcohol (II) in the presence of NaH gives rise to a mixture of mono- and diallylated compounds (III) and (IV) which, without separation, is subjected to Arbuzov reaction with triethyl phosphite, to furnish the desired phosphonate (V). Electrophilic fluorination of (V) using N-fluorobenzenesulfonimide provides the difluoro phosphonate (VI). Then, basic hydrolysis of phosphonate (VI) affords acid (VII). Compound (VII) is attached to a functionalized non-crosslinked polystyrene soluble polymer under Mitsunobu conditions to produce the polymer-bound phosphonate (VIII). Then, removal of the allyl group in the presence of p-toluenesulfinic acid and Pd(PPh3)4 yields the benzylic alcohol (IX). Oxidation of (IX) employing the Dess-Martin periodinane reagent leads to aldehyde (X) (1).

Wittig condensation of aldehyde (X) with the phosphorus ylide generated from phosphonium salt (XI) provides the polymer-bound cinnamate derivative (XII). Simultaneous cleavage of the support from (XII) and phosphonate deprotection to provide phosphonic acid (XIII) is achieved using bromotrimethylsilane. Acid (XIII) is then applied to an anion exchange resin and eluted with ammonium hydroxide to furnish the corresponding ammonium salt (1).