Vanillin (I) was protected as the tetrahydropyranyl ether (II) by treatment with dihydropyran in the presence of pyridinium p-toluenesulfonate. Similarly, hydroxyacetone (III) was converted to the corresponding tetrahydropyranyl ether (IV). Aldol condensation between aldehyde (II) and ketone (IV) using LDA in cold THF furnished the hydroxy ketone (V). Removal of the tetrahydropyranyl protecting groups of (V) under acidic conditions caused the dehydration of the beta-hydroxyl group, affording the unsaturated ketone (VI). The phenolic hydroxyl group of (VI) was then protected as the trimethylsilyl ether (VII). After protection of the phenolic hydroxyl group of ferulic acid (VIII) as the silyl ether (IX), coupling between (IX) and (VII) by means of DCC and DMAP provided the silyl-protected ester (X). This was finally desilylated by treatment with HOAc in aqueous THF.
A more direct procedure for the preparation of the title ester has been reported, consisting in coupling unprotected acid (VIII) with keto alcohol (VI) by means of DCC in the presence of DMAP and DMAP-hydrochloride.