合成路线1

4-Methylvaleric acid (I) was converted to acid chloride (II) and then condensed with (S)-4-benzyl-2-oxazolidinone (III) to give (IV). Subsequent alkylation of (IV) with tert-butyl bromoacetate (V) in the presence of sodium bis(trimethylsilyl)amide produced the chiral intermediate (VI), which was hydrolyzed with lithium peroxide to yield (R)-2-isobutylsuccinic acid 4-tert-butyl ester (VII). Further alkylation of (VII) with 4-bromo-1-butene (VIII) afforded a 6:1 mixture of syn/anti isobutenyl compounds (IX), which upon isomerization with LDA in THF at -20 C, followed by quenching with MeOH, provided a 1:1.5 mixture of isomers. Condensation of N-Boc-L-tyrosine (X) with methylamine in the presence of EDC and HOBt gave amide (XI). Then, removal of the Boc protecting group with HCl in dioxan yielded tyrosinamide (XII). This was coupled to succinic acid derivative (IX) using EDC and HOBt to afford the corresponding amide (XIII) as an epimeric mixture. Hydroboration of the butenyl double bond, followed by oxidative treatment with H2O2 produced alcohol (XIV).