合成路线1

The reaction of (LIII) with HF in pyridine/methanol gives the desilylated tricyclic intermediate (LIV), which is resilylated with TESCl and DMAP in dichloromethane and debenzylated by reaction with 1,4-cyclohexadiene over Pd/C to afford the free hydroxyacid (LV). The cyclization of (LV) by means of 2,4,6-trichlorobenzoyl chloride, i-PrNEt2 and DMAP gives the macrocycle (LVI), which is selectively deprotected with PPTS in methanol/HC(OEt)3/dichloromethane, and oxidized with Dess Martin periodinane (DMP) in pyridine/dichloromethane yielding the diketone (LVII). The reaction of (LVII) with the Fuji's chiral phosphonate (LVIII) by means of NaHMDS in THF affords the C13 enoate (LIX), which is condensed with methyl glyoxylate by means of KHMDS in THF to give the C21 enoate (LX). The stereoselective reduction of the carbonyl group of (LX) with BH3/SMe2 catalyzed by the oxazaborolidine (A), followed by esterification with methoxyacetic anhydride provides the methoxyacetate (LXI).