合成路线1

In a related synthetic method, N-Boc-tryptophan (II) was coupled with benzyl alcohol using EDC and HOBt to produce the corresponding benzyl ester (XIII). Incorporation of the methoxycarbonyl group into the indole N (XIV) was accomplished by treatment of (XIII) with dimethyl carbonate in the presence of DMAP. The Boc protecting group of (XIV) was then removed under acidic conditions to afford amino ester (XV). The dipeptide derivative (XVI) was prepared by coupling of amino ester (XV) with the N-carbamoyl aminoacid (XI). After hydrogenolysis of the benzyl ester group of (XVI), acid (XVII) was coupled with norleucine benzyl ester (XVIII) yielding tripeptide (XIX). Further benzyl ester hydrogenolysis in (XIX) gave the corresponding carboxylic acid, which was finally converted into the title sodium salt.