合成路线1

3-Methoxybenzonitrile (I) was converted to the corresponding imidate (II) by treatment with ethanolic HCl. Condensation of (II) with aminoacetaldehyde diethyl acetal (III) gave amidine (IV), which was cyclized with diethyl ethoxymethylenemalonate (V) in refluxing ethanol to yield the pyrimidinone (VI). Hydrolysis of the ethyl ester function of (VI) by treatment with LiI in hot pyridine provided acid (VII). This was subjected to a Curtius rearrangement with diphenylphosphoryl azide, and the intermediate isocyanate was condensed with benzyl alcohol to produce the benzyl carbamate (VIII). Acid hydrolysis of the diethyl acetal group of (VIII), followed by oxidation of the resulting aldehyde with sodium chlorite, furnished the carboxylic acid (IX).