The protected glutamic acid (I) is converted to the mixed anhydride (II) using ethyl chloroformate, and subsequently reduced to alcohol (III) by means of NaBH4. Swern oxidation of (III) provides aldehyde (IV), which is subjected to a Wittig condensation with triphenyl methylenephosphorane to afford olefin (V). Hydroboration of (V), followed by reaction with (+)-pinanediol (VI) leads to the boronate (VII). Finally, complete deprotection of (VII) with BCl3 yields the desired boronic acid.

The enantioselective alkylation of the nickel complex (I) of the Schiff base derived from glycine and (S)-2-[N'-(N-benzylprolyl)amino]benzophenone with 4-bromo-1-butene (II) affords the corresponding complex (III) of (S)-2-amino-5-hexenoic acid, which is subsequently hydrolyzed to the free aminoacid (IV) under mild acidic conditions. Esterification of (IV) by means of SOCl2 in methanol leads to amino ester (V), and further protection with di-tert-butyl dicarbonate provides the N-Boc derivative (VI). Hydroboration of the double bond of (VI) with diisopinocampheylborane, followed by in situ oxidation with acetaldehyde gives rise to the diethyl boronate (VII). This is then converted to the isolable pinanediol boronate (IX) upon treatment with (+)-pinanediol (VIII). Finally, total deprotection of (IX) by refluxing with 12 M HCl furnishes the title compound.