合成路线1

Mixed anhydride (II), prepared from N-Boc-L-norleucine (I) and isobutyl chloroformate in the presence of Et3N, was reacted with ethereal diazomethane to afford diazoketone (III). Then, homologation of (III) into b-amino ester (IV) was accomplished by treatment with silver benzoate and Et3N in MeOH. Subsequent hydrolysis of (IV) of the ester function with K2CO3 in aqueous MeOH, followed by Boc deprotection with HCl in dioxan furnished the b-amino acid (VI). After conversion to the trimethylsilyl amine with N-methyl-N-(trimethylsilyl)acetamide, amino acid (VI) was coupled with 2,2'-dithiobisbenzoyl cloride (VIII), prepared from acid (VII) and thionyl chloride, to yield the target bisamide.