合成路线1

Chiral pentanoic aldehyde intermediate (XIX): The reaction of the chiral benzoate ester (XII) with (c-Hex)2B-Cl and Me2EtN in ethyl ether gives the boron enolate (XIII), which is condensed with the propionaldehyde (XIV) to yield the benzoate ester (XV). The protection of the OH group of (XV) by means of p-methoxybenzyl trichloroacetimidate and Tf-OH affords the corresponding p-methoxybenzyl ether (XVI). The reduction of the ketonic group of (XVI) by means of LiAlH4 in THF or NaBH4 in methanol provides the alcohol (XVII), which is debenzoylated with K2CO3 in methanol to furnish the diol (XVIII). Finally the vicinal diol (XVIII) is oxidized with NaIO4 in aqueous methanol to obtain the target, chiral pentanoic aldehyde intermediate (XIX).