合成路线1

The known methyl ester (VI was hydrolyzed to carboxylic acid (VII) with LiOH in aqueous acetone. After conversion of (VII) to the corresponding succinimidyl ester with N-hydroxysuccinimide and EDC, fluoride-mediated desilylation under acidic conditions furnished alcohol (VIII). Subsequent esterification of (VIII) with the protected amino acid (IX) using EDC and a catalytic amount of DMAP provided intermediate (X). Then, chemoselective coupling of (X) with amino acid (V) was achieved in the presence of N,O-bis(trimethylsilyl)acetamide (BSA) in hot DMF to afford the acyclic precursor (XI). After removal of the Boc group of (XI) with trifluoroacetic acid, the resulting amino acid (XII) was converted to the cyclic depsipeptide (XIII) by macrolactonization under high dilution conditions in the presence of pentafluorophenyl diphenylphosphinate. The aryl amine of (XIII) was protected as the Fmoc derivative (XIV).