Abstract:
The cross-aldol condensation of N-benzyl-2,5-dideoxy-2,5-imino-3,4-O-isopropylidene-l-ribose with 4,6-O-benzylidene-2-deoxy-α-d-erythro-hexopyranosid-3-ulose (potassium enolate + HMPA) gave an aldol as the major product. DAST-induced water elimination gave two enones that were converted into the aza-C-disaccharides (+)-4 [methyl 2-deoxy-2-(1,2,5-trideoxy-2,5-imino-l-ribitol-1C-yl)-α-d-glucopyranoside] and (+)-5 (the α-d-allopyranoside analogue). Reduction of the aldol and deprotection provided aza-C-disaccharide (+)-3 {methyl 2-deoxy-2-[(1R or 1S)-2,5-dideoxy-2,5-imino-l-ribitol-1C-yl]-α-d-allopyranoside} with a hydroxymethano linker.
