合成路线1

Treatment of cyclopropane-1,1-dicarboxylic acid (IX) with one equivalent of SOCl2 in the presence of Et3N in THF at 0 °C, followed by condensation of the activated intermediate with 4-fluoroaniline (X), provides the monoamide (XI) , which is optionally chlorinated to (VIII) by treatment with oxalyl chloride in cold THF .
Reaction of 3,4-difluoronitrobenzene (XII) with sodium benzylate prepared from benzyl alcohol and NaH in dimethylacetamide gives 1-benzyloxy-2-fluoro-4-nitrobenzene (XIII) as the main product. Subsequent reduction of compound (XIII) by means of iron and ammonium formate in refluxing toluene leads to the corresponding aniline (XIV), which is subsequently coupled with carboxylic acid (XI) using EDC in CH2Cl2 to afford the diamide (XV). Finally, debenzylation of diamide (XV) by transfer hydrogenation with 1,4-cyclohexadiene and Pd/C in boiling EtOH provides the target intermediate (I) . Scheme 2. Alternatively, acid chloride (VIII) can be directly condensed with 4-amino-2-fluorophenol (XVI) in the presence of 2,6-lutidine in cold THF to give diamide (I) .