Coupling of N-Boc-L-tert-leucine (I) with (R)-1-phenylethylamine (II) using EDC and HOBt gave amide (III) which, after acid cleavage of the N-Boc group, provided amino amide (IV). Acylation of amine (IV) with (R)-2-allylsuccinic acid 4-tert-butyl ester (V) afforded the diamide (VI). Biphenylyl bromide (IX) was prepared by the Suzuki coupling between 5-bromo-2-iodotoluene (VII) and phenylboronic acid (VIII). The biaryl group was then introduced via Heck reaction of biphenylyl bromide (IX) with olefin (VI), yielding adduct (X). Subsequent hydrogenation of the olefin double bond of (X) over Pd/C afforded (XI). Carboxylic acid (XII) was then obtained by trifluoroacetic acid-promoted cleavage of the tert-butyl ester group of (XI). Conversion of (XII) to the title hydroxamic acid was then achieved by coupling of carboxylic acid (XII) with O-allylhydroxylamine (XIII), followed by O-allyl group cleavage in the presence of ammonium formate and palladium catalyst.

Coupling of N-Boc-L-tert-leucine (I) with (R)-1-phenylethylamine (II) using EDC and HOBt gave amide (III) which, after acid cleavage of the N-Boc group, provided amino amide (IV). Acylation of amine (IV) with (R)-2-allylsuccinic acid 4-tert-butyl ester (V) afforded the diamide (VI). Biphenylyl bromide (IX) was prepared by the Suzuki coupling between 5-bromo-2-iodotoluene (VII) and phenylboronic acid (VIII). The biaryl group was then introduced via Heck reaction of biphenylyl bromide (IX) with olefin (VI), yielding adduct (X). Subsequent hydrogenation of the olefin double bond of (X) over Pd/C afforded (XI). Carboxylic acid (XII) was then obtained by trifluoroacetic acid-promoted cleavage of the tert-butyl ester group of (XI). Conversion of (XII) to the title hydroxamic acid was then achieved by coupling of carboxylic acid (XII) with O-allylhydroxylamine (XIII), followed by O-allyl group cleavage in the presence of ammonium formate and palladium catalyst.