合成路线1

The condensation of gamma-butyrolactone (I) with phenethyl amine (II) at high temperatures afforded phenethylpyrrolidinone (III). This was alkylated with isobutyl iodide (IV) in the presence of lithium diisopropylamide in cold THF yielding the 3-isobutyl pyrrolidinone (V), and further alkylated with tert-butyl bromoacetate (VI) to give (VII). Subsequent alkylation of (VII) at the alpha-position of carboxylate group with allyl bromide provided (VIII). Ozonolysis of the double bond of (VIII), followed by reductive treatment with NaBH4 produced alcohol (IX), which was coupled with dibenzyl iminodicarboxylate (X) under Mitsunobu conditions giving (XI). The biscarbamate (XI) was deprotected by hydrogenolysis over Pd/C, and the resulting primary amine (XII) was condensed with 3,4-difluorobenzoyl chloride (XIII) to furnish amide (XIV). Then, trifluoroacetic acid-promoted cleavage of the tert-butyl ester of (XIV) provided the corresponding carboxylic acid, which was finally coupled with hydroxylamine by means of EDC and HOBt to afford the target hydroxamic acid