Total Synthesis of Nucleoside Antibiotics Amicetin, Plicacetin, and Cytosaminomycin A—D
Jiqiang Fu, Peng Xu, Biao Yu
Abstract
Main observation and conclusion Amicetin and congeners constitute a small family of complex pyrimidine nucleosides, which exhibit strong antibiotic activities against Gram‐positive bacteria and notably against strains of Mycobacterium tuberculosis . Herein, we report chemical synthesis of a series of disaccharide congeners of the amicetin family, including amicetin, plicacetin, and cytosaminomycin A—D. It is the first time for successful synthesis of amicetin, the prototypical member, and cytosaminomycins. The synthetic approach employs glycosyl N ‐phenyltrifluoroacetimidate and thioglycoside donors to construct the characteristic aminodeoxydisaccharides consisting of α‐(1→4)‐glycosidic linkage, uses gold(I)‐catalyzed N ‐glycosylation to furnish 2‐deoxy‐β‐nucleosides, and finally exploits amidation and global deprotection to complete the syntheses. It is noteworthy that the 3‐ O ‐protecting group in the 2‐deoxydisaccharide donors is found to be crucial for a successful N ‐glycosylation to assemble the cytosaminomycin disaccharide nucleosides.