合成路线1

The Keck's enantioselective allylation of dodecanal (I) with allyl bromide (II) employing a catalytic amount of (R)-BINOL and titanium tetraisopropoxide furnishes the chiral alcohol (III), which is esterified with acryloyl chloride (IV), TEA and DMAP to give the acrylate (V). The olefin metathesis of (V) by means of Grubbs' catalyst and Ti(O-iPr)4 in refluxing dichloromethane yields the dihydropyranone (VI), which is epoxidized with H2O2 and NaOH to afford the chiral epoxide (VII). The reductive cleavage of (VII) with diphenyl diselenide and NaBH4 gives the chiral tetrahydropyranone (VIII), which is silylated with Tbdms-Cl and DIEA, yielding the silyl ether (IX). Opening of the lactone ring of (IX) with TEA and methanol affords the hydroxyester (X), which is treated with dihydropyran and PPTS to provide the tetrahydropyranyl ether (XI). The desilylation of (XI) with TBAF in THF gives the beta-hydroxyester (XII), which is alkylated with hexyl iodide and LDA in THF, yielding the adduct (XIII). The cyclization of (XIII) by hydrolysis with LiOH, followed by treatment with Ph-SO2-Cl, affords the beta-lactone (XIV), which is treated with PPTS to eliminate the tetrahydropyranyl-protecting group and yield the secondary alcohol (XV). The esterification of (XV) with N-(benzyloxycarbonyl)-L-leucine (XVI) by means of DCC and DMAP affords the leucinate (XVII), which is deprotected with H2 over Pd/C, affording (XVIII) with a free amino group that is formylated with acetic formic mixed anhydride to furnish the target (-)-tetrahydrolipstatin.