Total Synthesis of Nucleoside Antibiotics Plicacetin and Streptcytosine A.

Disaccharide nucleoside antibiotics plicacetin and streptcytosine A (also named rocheicoside A) were effectively synthesized through the common precursor cytosamine. The amosamine and amicetose moieties were efficiently assembled through an α-selective O-glycosylation, and the cytosine nucleus was subsequently introduced through a β-selective gold(I)-catalyzed N-glycosylation. Further microwave-assisted amidation reactions completed the modular syntheses.