合成路线1

The stereoselective allylation of aldehyde (I) by means of allylmagnesium bromide (II) catalyzed by (-)-Ipc2BOMe gives the alcohol (III), which is protected with Tbdms-Cl and imidazole to yield the silyl ether (IV). The oxidation of the terminal double bond of (IV) by means of OsO4, NMO and NaIO4 affords the carbaldehyde (V), which is diastereoselectively condensed with the chiral bornanesultam (VI) by means of TiCl4 and DIEA in dichloromethane to provide the adduct (VII). The protection of the OH group of (VII) with Mom-Cl, NaI and DIEA in refluxing DME gives the Mom-ether (VIII). The reductive cleavage of the chiral auxiliary by means of LiEt3BH in THF yields the carbinol (IX), which is treated with Ts-Cl, TEA and DMAP in dichloromethane to afford the tosylate (X). The reductive cleavage of the tosyl group of (X) by means of LiEt3BH in THF provides the chiral methylated compound (XI), which is desilylated by means of TBAF in THF to give the corresponding alcohol (XII). The reaction of (XII) with benzoic acid (XIII) by means of DEAD and PPh3 in refluxing ethyl ether yields the benzoate ester (XIV), which is submitted to a ring closing metathesis (RCA) reaction by means of a Ru catalyst to afford the macrolactone (XV). The selective monodeprotection of (XV) by means of DDQ in dichloromethane/water provides the ethanol derivative (XVI), which is oxidized by means of DMP in dichloromethane to give the carbaldehyde (XVII). The homologation of (XVII) by means of a Horner-Wadsworth-Emmons reaction with phosphonate (XVIII) by means of NaH in THF yields the unsaturated allyl ester (XIX), which is treated with BBr3 in dichloromethane to eliminate the methoxy and methoxymethoxy protecting group, yielding the dihydroxy compound (XX).