合成路线1

Protection of (S)-3-hydroxy-2-methylpropionic acid methyl ester (I) as the corresponding silyl ether, followed by reduction with DIBAL provides the aldehyde (II). Diastereoselective aldol condensation of (II) with the chiral N-propionyl oxazolidinone (III) in the presence of dibutylboron triflate leads to adduct (IV), which is then reduced with LiBH4 to give the diol (V). The diol (V) is protected as the cyclic ketal (VII) by treatment with anisaldehyde dimethylacetal (VI) in the presence of pyridinium p-toluenesulfonate (PPTS). Desilylation of (VII) using tetrabutylammonium fluoride yields the alcohol (VIII). Subsequent iodination of (VIII) with I2/PPh3, followed by displacement of alkyl iodide (IX) with PPh3 in refluxing benzene, furnishes the phosphonium salt (X).