合成路线1

After protection of 1-benzyl-3-pyrrolidinone (I) as the corresponding ethylene ketal (II) with ethylene glycol and p-toluenesulfonic acid, N-benzyl group hydrogenolysis over Pearlman's catalyst provides the secondary amine (III). Subsequent condensation of amine (III) with 3,4-difluoronitrobenzene (IV) in hot DMF furnishes the N-aryl pyrrolidine (V). Reduction of the nitro group of (V) by transfer hydrogenation with ammonium formate and Pd/C leads to aniline (VI). This is further acylated with benzyl chloroformate producing carbamate (VII). Then, reaction of the lithium anion of carbamate (VII) with (R)-glycidyl butyrate (VIII) gives rise to oxazolidinone (IX). After conversion of alcohol (IX) to mesylate (X), the primary amine (XI) is obtained by Gabriel synthesis with potassium phthalimide, followed by hydrazinolysis. Acylation of amine (XI) with Ac2O produces amide (XII). The ethylene ketal of (XII) is then hydrolyzed with p toluenesulfonic acid in aqueous acetone, providing pyrrolidinone (XIII).