合成路线1

The cyclization of 2(R)-bromobutane-1,4-diol (VIII) by means of NaH in THF, followed by acylation with Ts-Cl gives the chiral epoxide (IX), which is treated with NaI in hot acetone to yield the iodo-epoxide (X). The enantiocontrolled condensation of (X) with the commercial imine (XI) by means of Cs-OH catalyzed by a chiral phase transfer catalyst affords the epoxy iminoester (XII). The reaction of the epoxy group of (XII) with N-methylbenzylamine in methanol provides the expected amino-alcohol (XIII), which is treated with citric acid to hydrolyze the imino group to give amine (XIV). Elimination of the benzyl protecting group of (XIV) by means of H2 over Pd/C yields the diamino ester (XV), which is cyclized to the hydroxy-caprolactam (XVI) by reaction with Na-OMe in methanol at 80 C in a sealed tube. The reaction of the OH group of (XVI) with tetradecanoyl chloride (XVII) by means of TFA affords the corresponding ester (XVIII). The condensation of the amino group of (XVIII) with the intermediate phenyl thioester (VII) in refluxing dioxane provides the corresponding amide (XIX), which is finally deprotected by a first treatment with DDQ in water/methanol/dichloromethane, followed by desilylation with PPTS in hot methanol/dichloromethane to yield the target bengamide B.