合成路线1

The intermediate (IV) has been obtained as follows: The condensation of silylated propionic aldehyde (I) with the mesylated acetylene (II) by means of Pd(PPh3)4 and Et2Zn in THF gives the hexanol (III), which is protected with chloromethyl (methyl)ether by means of DIEA and Bu4NI, yielding the desired acetylenic intermediate (IV) (1) The intermediate (XXII) has been obtained as follows: The desilylation of hexanol (III) with TBAF gives the acetylenic diol (V), which is protected with p-methoxy-benzaldehyde diethyl acetal (VI) catalyzed by CSA, affording the cyclic ketal (VII). The homologation of (VI) with formaldehyde and BuLi yields the propargyl alcohol (VIII), which is treated with Ac2O to provide the acetate (IX) (1). The partial hydrogenation of the triple bond of (IX) with Red-Al gives the allyl alcohol (X), which is asymmetrically epoxidated by the Sharpless method, yielding the epoxide (XI). The reduction of (XI) with Red-Al affords the chiral diol (XII), which is monoesterified with pivaloyl chloride and TEA to provide the pivalate (XIII). The silylation of (XIII) with Tbdms-OTf and lutidine furnishes the silylated pivalate (XIV), which is hydrolyzed with K2CO3 in methanol to give the primary alcohol (XV). The Swern oxidation of (XV) gives the aldehyde (XVI) (2), which is condensed with the intermediate acetylenic derivative (IV) by means of BuLi and LiBr in THF, yielding the adduct (XVII). The partial reduction of the triple bond of (XVII) with H2 over Pd/Pb/CaCO3 gives compound (XVIII) with a cis double bond. The protection of the OH group of (XVIII) as the methoxymethyl ether, followed by desilylation with HF in pyridine, yields the primary alcohol (XIX), which is oxidized with DMP to the corresponding aldehyde (XX). Finally, this compound is condensed with the iodophosphorane (XXI) to afford the target intermediate, the iodo compound (XXII).