合成路线1

The reaction of 3,5-dihydroxybenzoic acid (I) with Bn-Br, K2CO3 and 18-crown-6 in refluxing acetone gives 3,5-bis(benzyloxy)benzoic acid (II), which is reduced with LiAlH4 in ethyl ether to yield the corresponding benzyl alcohol (III). The reaction of (III) with PBr3 in ethyl ether/pyridine affords the benzyl bromide (IV), which is treated with triisopropyl phosphite (V) at 140-150 C to provide the phosphonate (VI). The condensation of (VI) with 4-benzyloxybenzaldehyde (VII) by means of NaOMe in DMF gives (E)-3,4',5-tris(benzyloxy)stilbene (VIII), which is finally debenzylated by treatment with BBr3 in dichloromethane. Alternatively, the synthesis of the target product can be performed by first condensation of 3,5-dimethoxybenzoyl chloride (IX) with 4-acetoxystyrene (X) by means of palladium(II) acetate and Et3N in p-xylene to yield (E)-4-acetoxy-3',5'-dimethoxystilbene (XI), whose acetoxy group is subjected to saponification either with NaOMe or with K2CO3 in THF/H2O/MeOH and whose methoxy groups are cleaved by means of BBr3 in CH2Cl2.