| Summary: | The first total synthesis of 5′-<i>O</i>-α-<span style="font-variant: small-caps;">d</span>-glucopyranosyl tubercidin was successfully developed. It is a structurally unique disaccharide 7-deazapurine nucleoside exhibiting fungicidal activity, and was isolated from blue-green algae. The total synthesis was accomplished in eight steps with 27% overall yield from commercially available 1-<i>O</i>-acetyl-2,3,5-tri-<i>O</i>-benzoyl-β-<span style="font-variant: small-caps;">d</span>-ribose. The key step involves stereoselective α-<i>O</i>-glycosylation of the corresponding 7-bromo-6-chloro-2′,3′-<i>O</i>-isopropylidene-β-<span style="font-variant: small-caps;">d</span>-tubercidin with 2,3,4,6-tetra-<i>O</i>-benzyl-glucopyranosyl trichloroacetimidate. All spectra are in accordance with the reported data for natural 5′-<i>O</i>-α-<span style="font-variant: small-caps;">d</span>-glucopyranosyl tubercidin. Meanwhile, 5′-<i>O</i>-β-<span style="font-variant: small-caps;">d</span>-glucopyranosyl tubercidin was also prepared using the same strategy.
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