合成路线1

Treatment of 3-nitro-1,8-naphthalic anhydride (I) with mercuric oxide and aqueous sodium acetate, and then with refluxing concentrated HCl provided a mixture of decarboxylation products (II) and (III). Condensation of this mixture with L-methionine methyl ester (IV) in the presence of dicyclohexylcarbodiimide and 1-hydroxybenzotriazole, followed by chromatographic separation of isomers, yielded the desired 6-nitronaphthalenecarboxamide (V). Further reduction of the nitro group with SnCl2 in ethanol gave amine (VI), which was reductively condensed with S-triphenylmethyl-N-Boc-cysteinal (VII) in the presence of sodium cyanoborohydride, acetic acid, and molecular sieves to afford (VIII). Then, hydrolysis of methyl ester with lithium hydroxide in THF-water gave acid (IX), and finally, deprotection of trityl and tert-butoxycarbonyl groups with an excess of trifluoroacetic acid in the presence of ethanedithiol provided the title compound as the trifluoroacetate salt.