合成路线1

The cyclization of the chiral diene (I) with acrolein (II) by means of BF3/Et2O in dichloromethane gives the chiral cyclohexene (III), which is dihydroxylated under Upjohn conditions (OsO4) yielding the dihydroxy compound (IV). The reaction of (IV) with acetone (V) and TsOH affords the isopropylidene derivative (VI), which is treated with NaOH in THF/water to eliminate the chiral auxiliary to yield the cyclohexene carbaldehyde (VII). The regio- and diastereoselective condensation of (VII) with bromide (VIII) by means of t-BuLi and BF3/Et2O affords the adduct (IX), which is treated with N-cyclohexyl-hydroxylamine (X) to provide the nitrone (XI). The reaction of (XI) with acetyl chloride gives the alpha-acetoxy-N-cyclohexylimine (XIII), through the intermediate (XII). The hydrolysis of (XIII) with AcOH and NaOAc yields the carbaldehyde (XIV), which is reduced with LiAlH4 in ethanol to afford the hydroxymethyl derivative (XV). The hydrolysis of the acetoxy and isopropylidene groups of (XV) by means of HCl in THF provides the tetrahydroxy derivative (XVI), which is converted into the epoxide (XVII) by a treatment with MsCl, TEA, DMAP and NaOH in dichloromethane. A new epoxidation of (XVII) by means of VO(acac)2 and t-BuOOH in benzene gives the bis-epoxide compound (XVIII), which is finally monomethylated by means of t-BuONa and MeI in THF to yield the target intermediate fumagillol (XIX).